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3

Assessment of the Current State of Technologies Involved in Naval Theater Missile Defense and an Evaluation of Current and Projected Department of the Navy Programs Designed to Meet the Evolving Threat

This chapter assesses the Department of the Navy's current and projected capabilities in theater missile defense and the status of the technologies involved. It begins with a summary evaluation of the Navy's and Marine Corps' overall current and projected capabilities in the three distinct missions: ASCMD, OCMD, and TBMD. Then the discussion turns to subsystems in order to focus on technology, treating, in turn, sensors, weapons, and BMC3 systems.

Central to the effective utilization of these technologies are concepts of operation for executing the missile defense missions. The committee sought, during several of the Navy and Marine Corps briefings, to understand the concept of operations that would be used in the conduct of expeditionary operations. In particular, the committee wished to learn how the theater missile defense operations might be coordinated with the other operations that would be taking place at the same time and in the same area. Various presentations indicated that aircraft would be operating to deliver and provide logistic support to Marine Corps units ashore and that fire missions would be executed by ships launching ERGMs and other land-attack weapons, as called for by the Marine Corps. The committee believes it is necessary to construct a concept of operations that uses whichever measures are necessary to ensure that the theater missile defense can be coordinated with the offensive operations in such a manner that both succeed without conflict or danger to friendly forces. The briefers were unanimous in the opinion that no such concept has yet been defined.



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Page 39 3 Assessment of the Current State of Technologies Involved in Naval Theater Missile Defense and an Evaluation of Current and Projected Department of the Navy Programs Designed to Meet the Evolving Threat This chapter assesses the Department of the Navy's current and projected capabilities in theater missile defense and the status of the technologies involved. It begins with a summary evaluation of the Navy's and Marine Corps' overall current and projected capabilities in the three distinct missions: ASCMD, OCMD, and TBMD. Then the discussion turns to subsystems in order to focus on technology, treating, in turn, sensors, weapons, and BMC3 systems. Central to the effective utilization of these technologies are concepts of operation for executing the missile defense missions. The committee sought, during several of the Navy and Marine Corps briefings, to understand the concept of operations that would be used in the conduct of expeditionary operations. In particular, the committee wished to learn how the theater missile defense operations might be coordinated with the other operations that would be taking place at the same time and in the same area. Various presentations indicated that aircraft would be operating to deliver and provide logistic support to Marine Corps units ashore and that fire missions would be executed by ships launching ERGMs and other land-attack weapons, as called for by the Marine Corps. The committee believes it is necessary to construct a concept of operations that uses whichever measures are necessary to ensure that the theater missile defense can be coordinated with the offensive operations in such a manner that both succeed without conflict or danger to friendly forces. The briefers were unanimous in the opinion that no such concept has yet been defined.

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Page 40 Joint doctrine has been promulgated to guide the conduct of air and missile defense in a theater;1 however, the doctrine appears to presume that the theater has already been developed and that joint forces are in place. Other than to note that the same functions must be performed in undeveloped theaters, the joint doctrine is not helpful as a guide for expeditionary warfare. Although work is ongoing to evolve this doctrine at the Joint Theater Air and Missile Defense Organization (JTAMDO), the committee is not aware of any efforts to address the expeditionary warfare setting.2 Pending the development of doctrine to guide initial operations in an undeveloped theater, it falls to the Navy and Marine Corps to define the appropriate CONOPS. A CONOPS for expeditionary warfare in the littorals must address conflicting requirements for employment of operational assets and for control of offensive and defensive operations. Concepts for conduct of the offense are amenable to preplanning to avoid conflict yet must remain flexible enough to support operations ashore by Marine Corps units that may become subject to variation because of real-time events. At the same time, and in the same area, defensive measures must be taken to defeat ballistic missile, cruise missile, and aircraft threats to forces in the area, both afloat and ashore. The conduct of effective theater missile defense without disruption of and conflict with offensive measures is a very difficult task but a necessary one. However, several briefers told the committee that no concepts for coordinating offensive and defensive operations have been worked out. Developing such concepts is critical to the conduct of expeditionary warfare and deserves considerable effort. Such concepts are also necessary to a proper evaluation of the adequacy of theater missile defense programs. 3.1 OVERVIEW OF THEATER MISSILE DEFENSE CAPABILITY As discussed briefly in Chapter 1, the Department of the Navy's mission, which is to operate in the littorals and influence events ashore, has a strong impact on TMD requirements, and—as discussed in Chapter 2—the air threat 1 Fulford, LtGen C.W., Jr., USMC, Director, Joint Staff. 1999. “Joint Doctrine for Countering Air and Missile Threats,” Joint Publication 3-01, The Pentagon, Washington, D.C., October 19. Available online at <http://www.dtic.mil/doctrine/jel/new_pubs/jp3_01.pdf>; Ross, Lt Gen Walter K., USAF, Director, Joint Staff. 1996. “Doctrine for Joint Theater Missile Defense,” Joint Publication 3-01.5, The Pentagon, Washington, D.C., February 22. Available online at <http://www.dtic.mil/doctrine/jel/new_pubs/jp3_0l_5.pdf>. 2 Joint Theater Air and Missile Defense Organization and Ballistic Missile Defense Organization. To be published. "Annex G: GTAMD 2010 Operational Concept (Draft Version 5 (Unclassified - For Official Use Only))," from 1999 Theater Air and Missile Defense (TAMD Master Plan (U), The Pentagon, Washington, D.C., December 2 (Classified).

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Page 41 continues to become more difficult. This section discusses the effect of these factors on overall naval capabilities in ASCMD, OCMD, and TBMD. Because antiship missiles in the hands of potential adversaries are so numerous, so sophisticated, and so widespread, and because every naval combatant becomes a target whenever it enters the theater and must defend itself well so as to be an asset rather than a liability, ASCMD must be the Navy's highest priority in TMD. While the Navy's current capabilities are inadequate against antiship cruise missiles and its funding plans insufficient to protect some classes of ships against them, the Service has in hand the fundamental framework for effective defense against foreseeable ASCM threats. However, the Department of the Navy has not come to grips with the rapidly approaching necessity for overland cruise missile defense. In the future, adversaries will employ land-attack cruise missiles to deny U.S. forces needed access to ports and airfields in theaters of war. In the fundamental framework for an OCMD system, important elements are missing. Because tactical ballistic missiles are widespread weapons of terror and potential mass destruction and are poised today to deny U.S. access into theater, the nation needs, as soon as possible, a capability that will provide TBMD for ports and airfields until assets of other Services are in place. The Navy's burgeoning TBMD capability divides into two parts: area- and theater-wide systems. There are clear differences in how well the two systems are progressing toward an effective operational capability. The NAD system promises robust local defense against the short- to medium-range TBMs prevalent today and appears to be progressing smoothly. The NTW system, on the other hand, is a demonstration, not an acquisition program. The activity lives year to year on funding provided through congressional plus-ups. Its initial capability, if indeed it becomes a funded acquisition program and the Program Executive Office for Theater Surface Combatants' current plans for it continue, will be limited by SPY-1 radar performance, which in some geographic scenarios is inadequate to provide the wide defensive coverage needed to deal with the threat of ever-longer-range TBMs. Furthermore, since adequate TBMD requires defense in depth, a Navy theaterwide capability will one day be required. The next subsections delve further into the three mission areas (ASCMD, OCMD, and TBMD). 3.1.1 Antiship Cruise Missile Defense For the past half century or more, naval battle groups have been defended in several layers. The outermost layer has been air-to-air combat, a capability to “shoot the archer.” In recent decades, Aegis ships have provided the second layer, an umbrella of area defense over the battle group. Once the most important layer in battle group defense in depth, area defense now yields primacy to self-defense, largely owing to the severity of low-altitude threats. Nevertheless,

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Page 42 area defense can help in important situations such as the close-escort protection of aircraft carriers. Beginning with the AAW capstone requirements document (CRD) in 1996, the Navy has characterized the AAW performance of various ship classes in terms of a “probability of raid defeat,” whereby a raid is considered to be defeated if no threat missile penetrates the defense to hit the ship. The Navy defines the “probability of raid defeat” as a weighted sum of results against a specific raid (e.g., x low-altitude, low-observable, subsonic cruise missiles in y seconds). The CRD varies the x and y and the required “probability of raid defeat” by ship class. The committee takes no exception to the numbers in the CRD. The weightings are done across different classes of threat. A present-day low-altitude, low-observable, subsonic cruise missile is an example of class. The CRD does not specify the weightings. The Navy practice has been to give a heavy weight to the moderate cruise missile threats predominant today and much less weight to the more difficult threats, which are expected to emerge in the future or—if they already exist—are less numerous. This weighting tends to have a stronger effect on ship classes with less stringent requirements. The Navy justifies the CRD requirements and the weighting practice as a way to allocate scarce funds, because it cannot afford to defend all ships equally. This is no doubt so. However, the committee fears that such a practice tends to obscure real vulnerabilities. The adversary will decide which ship to attack and with what missiles. The adversary may “win” (if, for example U.S. popular opinion turns against further action) by attacking and sinking a less-well-defended ship with the best cruise missile it can buy. Some ship classes will not have to operate for long periods of time in the littorals and be exposed to the full threat, but others will. The committee believes that any ship so exposed should have the benefit of the best defense the Navy can provide. In the past, the air cover provided by Aegis ships was effective over a large area. Self-defense systems on some ship classes lagged in capability, but robust area defense gave Navy battle groups a good overall AAW capability. Today, with typical ship formations, the ability of one ship to defend another against some of the most dangerous antiship cruise missiles is almost nil, because the threats fly too low and too fast. As the information presented to the committee by a number of Navy offices clearly shows, the Navy's overall current operational capabilities in antiship cruise missile defense are marginal and declining. In recognition of this, the Navy has been investing heavily in a number of new detection, control, and engagement systems and also in systems integration. When these new capabilities are fielded, antiship cruise missile defense will be markedly improved for the ships that receive them. The committee is confident that the Navy has in hand the framework for antiship cruise missile defense. It consists of a combination of volume-search and horizon-search radars, well-automated fire control and doctrine that permits

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Page 43 fast response through automated decision-making in high-threat situations, defensive missiles that match the sophistication of the threat, and a netted capability that enables distributed ships to fight as a coherent whole. These elements, fielded on the right ships in adequate numbers and in timely fashion, should enable the Navy to counter foreseeable antiship cruise missile threats. Ships that do not receive these upgraded capabilities will remain vulnerable. The current program of record does not fully deploy the new capabilities. For example, it appears that ships other than Aegis cruisers and destroyers will lack an adequate engagement capability. A launcher for the ESSM will not be available on these vessels, and they must depend on the rolling airframe missile (RAM). Nor does the current program of record field capabilities to cover all the potential electronic countermeasure threats. The committee believes that the Department of the Navy should prioritize funding so that every combatant that conducts sustained operations in contested littoral waters is adequately defended. In summary, providing adequate defense against antiship cruise missiles will require reprioritization of funding, but the fundamental framework for ASCMD is there. 3.1.2 Overland Cruise Missile Defense As mentioned earlier, the committee believes that the Department of the Navy has not come to grips with the rapidly approaching necessity for an overland cruise missile defense. Important elements are missing from the fundamental framework for such a system. In the past, the Marines carried improved Hawk batteries into the theater for overland air defense, primarily against aircraft threats. Then, in the interest of mobility, they retired this improved system, which was bulky. The Marine Corps is now developing a point defense capability, but for the foreseeable future, U.S. forces entering the theater will have no wider defense coverage until the Army's Patriot batteries can be put in place. The Marine Corps operational strategies, OMFTS and STOM, will require the Navy to provide layers of air defense overland. Carrier-based manned aircraft can be counted on to keep enemy manned aircraft at bay, but in the future the enemy may use land attack cruise missiles to attack fixed objectives such as ports and airfields. As discussed in Chapter 2, land attack cruise missiles are not common today, but the nation's current weaknesses in countering them may hasten their development and deployment. If Navy platforms are to provide an overland cruise missile defense, there must be a capability to detect, track, and intercept cruise missiles that are beyond the line-of-sight horizon of ships at sea. One possible operational concept for OCMD includes an airborne platform for detection, weapon launch from a surface ship, in-flight control by the ship based on the airborne platform's track (“engage on remote”), and active terminal guidance by the weapon. Alternative-

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Page 44 ly, the airborne platform could control the weapon in flight (“forward pass”) or it could illuminate the target for semiactive homing by the weapon. Whichever concept is considered, major elements are missing. The Navy has no airborne platform capable of detecting a low-observable cruise missile overland. It has no ship-launched, actively guided air defense weapon. It has no airborne illumination capability. The Department of the Navy is unprepared for a defense against land-attack cruise missiles and is not funding development to rectify the situation. 3.1.3 Theater Ballistic Missile Defense The NAD system will implement a TBMD capability on all Aegis cruisers and destroyers. The NAD system requires changes to the SPY-1 radar, to the Aegis weapon control system, and to the standard missile (SM). The system is being designed to defend a limited region around the ship against short- to medium-range TBMs. The reach of the system will enable ships to operate a few tens of miles offshore and defend assets a few tens of miles inland. While the SPY-1 radar will be taxed, improvements under way in the NAD program should enable it to detect TBMs at ranges matched to its interceptor's kinematic range. Engagements with the NAD system will occur well within Earth's atmosphere, and atmospheric drag will strip away much of the confusing debris around the TBM warhead, simplifying the target discrimination problem. The NAD interceptor, denoted SM-2 Block IVA, employs the propulsion stack of a currently operational SM-2 variant and adds an IR guidance system, among other things. It operates deep in the reentry region and uses aerodynamic maneuvering. This region is where threat RVs may also maneuver either inadvertently or deliberately. Short-range TBMs have low velocities and cannot maneuver very strongly. The high-g capability of the SM-2 together with its warhead should give it reasonable single-shot or salvo capability against these targets. The NAD system, as described to the committee, appears to be well structured and, except for the inadequate funding for the spiral development evolution, appears to have a well-defined development path that is supported by good analytic underpinnings. The system strengths and limitations are well understood and are being treated appropriately. The NAD system objectives for tactical ballistic missile defense are realistically limited and clearly stated. The performance of the system against its design threats was presented clearly and not overstated. The area TBMD challenge is a formidable one, and the Navy and DOD should probably expect some setbacks in the course of development, but the conceptual design and the program to develop it appear sound. Like the NAD program, the NTW effort intends to build on the Aegis legacy. However, the longer-range TBMs the NTW system is intended to counter and the much broader areas it is intended to protect place a far greater burden on the system. The NTW system will employ a highly modified standard missile

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Page 45 (SM-3), with the original warhead/seeker stage replaced by a new third-stage motor and a HTK vehicle. With a much lighter final payload, the interceptor burnout velocity is much greater, permitting much longer fly-outs and thus much larger defended regions. To get the large coverage, the SM-3 is designed to intercept exo-atmospherically, which necessitates launching the interceptor much earlier in the threat missile trajectory. The weakest link in the proposed phase I NTW defense is the detection capability the Navy will obtain by evolutionary improvement of Aegis's SPY-1 radar. In geographic situations where the NTW ship can be placed near the TBM launch point, the protected region can be very large. However, in situations where the NTW ship is near the TBM aim point, the protected region can be very small, limited as it is by SPY-1's detection capability. The committee believes that, certainly in NTW phase I and probably beyond, the Navy must devise concepts of operation that take advantage of detection assets not organic to the battle force. Forward-placed or space-based assets that detect TBMs early in flight would, through CEC or a similar link, enable midcourse control of NTW interceptors in order to greatly increase the size of the defended footprint in unfavorable geographies. The Navy is considering a new generation of shipboard radars for TMD. Achieving adequate detection and discrimination for NTW ships will be a driving requirement. One concept combines an S-band volume-search radar (much more powerful than SPY-1) with an X-band radar for horizon-search against cruise missiles and for long-range TBM discrimination. Because the severity of the near-term threat calls for fielding an NTW capability quickly, because many engineering challenges must be overcome to field even a limited NTW capability, and because the Navy will surely benefit considerably from experience gained in beginning to use the system as soon as possible, the Navy is considering fielding the so-called Block I NTW system. It is clear, however, that during the years it will take to field the system, the TBM threat will become even more severe, especially in the use of penetration aids, partly in response to the advent of the NTW system itself. The Navy's informal plans call for a Block II capability against a more severe threat, but the R&D to solve the challenges Block II will face is dragging. The committee also believes that in some geographic scenarios, the NTW system may ultimately need to depend on detection capabilities not organic to the ship in order to achieve wide defensive coverage. 3.2 SUBSYSTEM TECHNOLOGY ASSESSMENT The next subsections assess the state of technologies in the subsystems employed in the Department of the Navy's TMD. The technologies involved in sensor and weapon subsystems are the primary focus, but weapon control and electronic warfare are also discussed.

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Page 46 3.2.1 Sensors Because requirements and technologies are so diverse in different parts of the theater missile defense realm, the discussion of sensors is divided into assessment of technologies for (1) shipboard TBMD sensors, (2) National sensors for TBMD, (3) sensors for overland cruise missile defense, (4) sensors for anti-ship cruise missile defense, (5) sensors for air-to-air combat, and (6) sensors for electronic warfare. 3.2.1.1 Shipboard TBMD Sensors The role of the sensors in a TBMD system is to detect, locate, track, and identify the RV and to provide information that will permit an interceptor to hit it. This section focuses on the pre-weapon-commitment sensor, which is generally a surface-based radar that may be augmented by space or airborne IR sensors. The sensors used by interceptor seekers are discussed in Section 3.2.2.1, “TBMD Weapons.” Ballistic missiles generally arrive from high altitudes at high angles of elevation. Thus, detection range rather than terrain masking or clutter is generally the limiting factor in the TBMD performance of a surface radar. Once a nonmaneuvering RV has been detected, its probable impact area is easily determined. Generally, the problem of distinguishing friend from foe is of little importance in TBM encounters. However, because a large number of objects can follow essentially parallel exo-atmospheric trajectories, discrimination of the RV from incidental debris or deliberate decoys can be a significant problem. The area of coverage of a TBMD system can be obtained by a time-line analysis of the events along the trajectory and of when the defense functions of detection, identification, and interceptor launch and intercept can be carried out. The defended area of coverage is determined by how far the interceptor can fly in the time between interceptor launch and intercept. These times are determined by how well the target must be located and identified by interceptor kinematics and by the last point on the TBM trajectory at which a successful interception can be accomplished. These parameters differ for different threats, different radars, and different interceptors. Some of the issues affecting radar design and some candidate radars for TBMD systems are discussed below. Each of the radar functions is addressed to a top level of detail, including autonomous search, cued search, discrimination, and handover to the interceptor. The performance of each function depends on radar parameters such as power, aperture, frequency, and bandwidth. The range at which a radar can do autonomous search varies as the fourth root of the power-aperture product times the RCS of the target. Radar power and aperture are limited by cost and transportability requirements. Except to the extent that target RCS may be a function of frequency, autonomous search per-

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Page 47 formance is not a function of frequency. However, since power and aperture are generally cheaper at low frequencies, search radars tend to be designed to operate at lower frequencies as appropriate to U.S. radars. The threat generally consists of a number of objects—reentry vehicle (RV), debris, deliberate decoys, discarded booster stages, and so on—each of which has an RCS value. Thus, each will be detected at a different range. The booster will probably be the first thing to be detected by a surface radar. It may be detected either in autonomous search or in directed search as a result of cueing by an up-range radar or other detection sensor. After booster burnout, radar data can provide the basis for a good estimate of the booster impact point. For most TBM systems, the booster impact will be close to the RV impact point. Depending on the specific TBM system, the RV may be known to stay relatively close to the booster. This information permits the launch of an interceptor toward the predicted location of the booster. When the interceptor approaches the booster-RV pair, the location of the RV will be resolved by either the surface radar or the interceptor seeker in time to divert the interceptor and kill the RV. The radar can also do a local search in the vicinity of the booster looking for smaller targets. Since the radar energy can be concentrated in a smaller region, the detection range for these smaller targets can be much greater (often by a factor of 2 or more) than that with autonomous search. Since the radar beam width is narrower at higher frequencies (for fixed aperture size), cued search is generally more effective at high frequency. This is the case for discrimination also. Exo-atmospheric discrimination of both incidental debris and deliberate countermeasures generally relies on looking at the time history of the target RCS or a range- and/or Doppler-resolved RCS map of the target. This requires enough resolution so that different parts of the target appear in different range or Doppler resolution cells. Such resolution is available only at frequencies of S-, C-, or X-band, with the finest resolution at X-band. The use of higher frequencies is limited by attenuation in heavy rain or dense clouds if the radar is oriented toward the horizon and propagates over long distances. For TBMD systems, the radar is generally oriented to search high angles of elevation. In such circumstances the distance that the beam propagates through moisture-laden regions is relatively short. Thus, rain attenuation in TBMD radars may be tolerable at X-band frequencies but not at higher frequencies. For long-range AAW, the radar is designed to search at low elevation angles, and X-band suffers too much attenuation for practical designs. That is why radars with a long-range AAW mission, such as SPY-1 or Patriot, operate at S- or C-band frequencies. The final function of the surface radar is to hand over the identified target (or threat volume) to the missile seeker. There is a premium for making this handover as accurately as possible for two distinct reasons. First, the requirements on seeker acquisition range are a strong function of the handover accuracy, as is discussed in the section on weapons, below. Second, even if the radar can identify the RV uniquely, if there are other nearby targets, the seeker may

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Page 48 not be able to discriminate the RV from another target because its resolution cell has a shape different from that of the radar uncertainty volume. Ground or aircraft radars generally measure range very accurately and measure angle fairly crudely. The radar uncertainty volume is pancake-shaped, with the diameter of the pancake generally hundreds of times larger than the thickness. A ground or airborne radar forms one of these pancakes for each target in the vicinity of the RV and can pass this information—called a target object map (TOM)—to the interceptor. When the IR sensor on the interceptor looks at these pancakes, it can distinguish different angular positions but does not measure range. Unless the interceptor sensor has a radar capability in addition to an IR capability, the uncertainty region of an interceptor's IR sensor will be conical. If the seeker cone for a particular target cuts through more than one radar pancake, the seeker may not be able to uniquely associate the targets it detects within its cone of uncertainty with one of the radar targets and may, as a result, home on the wrong object. The performance of this function depends on the spacing of threat objects relative to the radar pancake diameter. The radar uncertainty volume is a strong function of radar antenna design and frequency, with higher frequency radars providing narrower beams and higher signal-to-noise ratios, resulting in much more accurate handovers. This handover to the interceptor is an essential fire control function, and the critical need for accuracy is the reason that fire control radars are generally at the highest frequency to propagate in all kinds of weather. A number of different radars (and other sensors) have been considered for use in ship-based TBMD systems. The capabilities of the current SPY-1 radar and potential upgrades are assessed first, those of other TBMD radars such as THAAD and Patriot are assessed next, those of National sensors, such as the Defense Satellite Program (DSP) and the SBIRS, are assessed last. The NAD system is a straightforward upgrade of the Aegis AAW system that incorporates modifications to the interceptor, the radar, and the software to permit attacking ballistic targets late in reentry. It does not require very long range or sophisticated discrimination, and the current SPY-1 is suitable for this job. The NTW system would enable a completely new mission. To get the large coverage, the NTW interceptor (SM-3) is designed to intercept exo-atmospherically, which necessitates launching the interceptor much earlier in the threat missile trajectory. The RV must be detected and identified earlier and at relatively long ranges. The current SPY-1 does not have the sensitivity to detect small RVs at the ranges needed to support the fly-out capability of the SM-3 and must depend on another SPY-equipped ship or other radar to provide track information at longer ranges. A number of approaches to solving this problem exist, and all of them are being considered. The long-term solution is to develop a new or upgraded radar with sufficient sensitivity. Analysis indicates that such a capability will require an improvement in detection range by at least a factor of 2, which translates into

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Page 49 an improvement in sensitivity by a factor of 16 (or 12 dB). The committee was told that the Navy is conducting several “radar roadmap” studies to coordinate radar developments for both NTW and NAD. Some of the candidates for the NTW (Block II) radar include a separate X-band TBMD-only radar similar to the THAAD radar and an S-band or S- and C-band radar to do both TBMD and AAW. The radar detection range depends on the target RCS, and a radar that is adequate for one particular RCS level may be inadequate or overdesigned for a smaller or larger target. The development and acquisition of a new radar will take a number of years. In the meantime, the NTW system can get some useful capability out of the current SPY-1 radar by taking advantage of ship deployment flexibility in some scenarios and of good knowledge of the threat TBMs in other scenarios. In several important cases (e.g., near the coast of North Korea), the NTW ship could be sited near the TBM launch point and could detect a large RCS booster at relatively short range. It could then do a cued search for the RV before it got out of range. The SM-3 has enough velocity to catch many TBMs even in a near-tail-chase geometry. If the ship cannot get close enough to the launch point to be able to detect the RV, it could use its knowledge of the TBM geometry to launch the interceptor toward the booster and have the seeker acquire the RV in time to divert. However, where the ship must be deployed downrange from the impact point, radar detection of the RV generally occurs too late to conduct a successful intercept. An upgraded radar is required for these cases. Figure 3.1 and Figure 3.2 show how the requirements for radar range and interceptor velocity can be traded off for both terminal-phase and ascent-phase operation using an exo-atmospheric interceptor. In this example, the incoming missile's reentry angle is assumed at 45 deg, its altitude at burnout is assumed at 75 km, and its velocity is assumed at 2.5 km/s. This analysis is highly simplified, using flat-earth and straight-line, constant-speed trajectories for both target and interceptor. Although the numerical results are only approximate, the example shows the difference in dependencies on radar range and interceptor velocity between terminal-phase defense and ascentphase defense. In terminal defense operation, the forward footprint distance is a measure of coverage (e.g., the distance that the impact point is forward of the defense site). The results show that the coverage can be increased by increasing the radar range to give the interceptor more time to fly out or by increasing the interceptor speed to let it fly further in the same time. The curve for zero footprint corresponds to self-defense. In ascent-phase operation, the parameter of the curves is the standoff distance, the distance (downrange) from the TBM launch point to the defense site. The curves differ significantly from those for terminal operation. If the interceptor is faster than the target (2.5 km/s in Figure 3.2 ), a fairly short-range radar may be adequate. It can detect booster burnout, determine the intercept point,

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Page 83 ~ enlarge ~ FIGURE 3.9 BMC3 system architecture. DMS, defense message system; OTCIXS, officer in tactical command information exchange subsystem; TADIXS, tactical data information exchange system; CUDIXS, common user data information exchange system; NAVMACS, naval modular automated communications system; TACINTEL, tactical intelligence information exchange system; JTT, joint tactical terminal; CTT, commander's tactical terminal; TIBS, tactical information broadcast service; TDDS, tactical receive applications (TRAP) data dissemination system; ADS, advanced display system; CDLMS, common data link management system. receives its data input from the CEC, which are netted Aegis radars, as well as from the TADILs and GCCS-M data sources. The Navy has been experiencing interoperability problems as it upgrades the components of this module. Those problems appear to be in the process of resolution. In the longer term, the Navy intends to replace this module with the so-called Aegis common command and decision system (CC&D), which will be based on a modular, open architecture that should help to minimize future interoperability problems. The TADILs and CEC are essential for providing the sensor input necessary for the BMC3 process. Of the three TADILs shown in Figure 3.9, Link 16 is the primary one in Navy plans. Thus, CEC and Link 16 are discussed in more detail below. National information feeds (coming from the left-hand box) are also important, especially for cueing sensors. While there is no further detail to be presented here, it should be noted that the timeliness of delivering these data could stand improvement.

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Page 84 The quality of the situational picture derived from the input data is of course critical and is a matter of much concern. A new effort, the SIAP System Engineering Office Program, is being established to address this concern. In addition, the area air defense commander (AADC) module has been established to provide a display capability to help time-critical (but not real-time) decision making and non-real-time planning. Both the SIAP program and the AADC module are discussed in more detail below. 3.3.4 Link 16 Describing Link 16 is complicated because it is many things rolled in one—it describes an RF communications network architecture, provides a message set for conveying information through the network communications, and defines procedures for the way in which this information will be gathered. 3.3.4.1 Current Capabilities Link 16 describes a networking scheme and message set that are instantiated in radio terminals. The JTIDS and its slightly more modern variant, the multi-function information distribution system (MIDS), are the Navy's terminals of choice. These terminals will be installed on a variety of aircraft, surface ships, and submarines over the next several years, as well as in Patriot and THAAD forces. Original JTIDS development (and the corresponding Link 16 specification) dates back at least 30 years; thus, even though it is just being deployed now, it is very much a legacy capability. Link 16 uses a time division multiple access (TDMA) networking scheme.5 In the basic configuration, this means each participant on the net can transmit only in its allocated time slot and must be in receiving mode the rest of the time. If only one time slot is allocated to a participant, Link 16 will transmit once every 12 seconds. It is possible to establish multiple independent networks simultaneously by giving each net a different frequency hopping pattern for its transmissions. In general, the TDMA scheme is very complex to arrange and quite demanding on operator skills. Up to a week or two can be required to develop and test the scheme to be used in an actual operation. Thus, Link 16 does not currently support flexible, rapidly conceived operations. The maximum capacity of the JTIDS (or MIDS) radio in antijam mode is 115 kbps (and often much less in practice),6 a low figure by modern information transfer standards and one that limits the utility of JTIDS. This is significant, because DOD has mandated that JTIDS (or variants such as MIDS) will provide 5 Details are given in Appendix C. 6 Appendix B provides an analysis of capabilities and limitations of Link 16.

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Page 85 the basic tactical communications capability. A more modern approach based on commercial technology would appear to greatly increase bandwidth. As discussed in Appendix C , commercial wireless technology is advancing rapidly, and capacities of at least a few megabytes per second currently appear possible. The commercial technology appears to have the necessary quality of service for military applications, although jam resistance is not a significant factor in the commercial developments. Still, the commercial technology would offer a good base upon which to build a jam-resistant capability. The Link 16 fixed-format message set—called the J-series messages—covers a wide range of information categories. Very important among these, of course, is the surveillance tracks detected by participants in a Link 16 net. To obtain the best data on a given target and avoid redundant tracks, Link 16 procedures call for the platform with the “best” track to have reporting responsibility and to be the only platform to report that track. In practice, this can lead to significant difficulties. Other message sets allow for mission assignment to attack a target, and still others provide precision position location information (PPLI) based on packet time-of-arrival measurements. This PPLI information allows for relative navigation and also serves as an identification means. Since the Link 16 message set was developed in the context of air defense, it covers the sort of information needed for cruise missile defense. Ballistic missile defense, however, required new messages to be added—for example, messages referring to missile launch and predicted impact points, space tracks, and engagement status. These additional messages take a shoot-and-shout approach to ballistic missile defense, but they do not provide coordination among multiple platforms that could fire at a given ballistic missile. 3.3.4.2 Planned Improvements Operational experience such as was gained in the Kosovo air war indicated significant shortcomings in TADIL operation. At times, significant portions of the air picture were missing because different tactical data links (Link 16 and others) would not interoperate with one another. Better TADIL network management is necessary. To promote that, the position of JICO has been established, and procedures for its operation have been defined. 7 In addition, there are plans to develop an automated tool to help the JICO in conducting network management. While these procedures and the automated tool, coupled with training for the individuals involved, should aid TADIL network management, they underscore the complexity of TADIL operation and the need to adopt more modern network technology allowing simpler management. 7 Joint Staff. 2000. Joint Data Network (JDN) Operations, CJCSM 3115.01, The Pentagon, Washington D.C., September 1.

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Page 86 TABLE 3.2 Planned Improvements and Potential Benefits Planned Improvement Potential Benefit Dynamic network management system (DNMS) for Link 16 Incremental increases in the flexibility of Link 16 networks, perhaps coupled with greater ease of planning and configuring such networks Enhanced throughput Higher bandwidth communications across Link 16 radio channels Optimized relative navigation More accurate relative position and time information for Link 16 platforms Joint range extension, S-TADIL J Increased ability to transmit J-series messages across non-JTIDS radio channels Link 16/JVMF advanced concept technology demonstration Gateways between Link 16 radios and their messages, on the one hand, and the Army's messaging system on the other Link 16 missile and tactical terminal (LMT2)/TacLink weapons Tactical command and position/location links to guided munitions SOURCE: Information derived from McCloud, Kenneth L., “PMW 159 Advanced Tactical Data Link Systems (ATDLS) Program Office,” briefing to the committee on July 26, 2000, Space and Naval Warfare Systems Command (PMW 159A), Arlington, Va. The advanced tactical data link systems (ATDLS) program office (SPAWAR PMW 159) develops improvements to Link 16 and related TADILs. These improvements are summarized in Table 3.2. In general, the committee supports these improvements, although it expresses some particular reservations in the more detailed discussion in Appendix B. These improvement programs have technical merit and are likely to provide substantial benefits to the Navy. However, they are best viewed as late-life upgrades to a system that is nearing the end of its technical life cycle. Serious consideration needs to be given to a much more modern approach to tactical data links. Such an approach would use a well-defined layered structure, as in Internet technology, instead of mixing the distinct problems of radio frequency (RF) channel architecture and message format, as Link 16 has done. Such an approach would also build on the rapid advances now occurring in commercial wireless technology. 3.3.5 Single Integrated Air Picture A SIAP is said to be the “product of fused, near-real-time and real-time data from multiple sensors to allow development of common, continuous, and unam-

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Page 87 biguous tracks of all airborne objects in the surveillance area.”8 This is the desired result of the integration of situation inputs in Figure 3.5, above. Such a result does not now pertain. Instead one finds missing tracks, multiple track designations for one object, track number swaps between objects, and object misidentification. These shortcomings have been manifest in real-world operations and detailed exercises such as the all -Service combat identification evaluation test (ASCIET) series. The preceding section highlighted the problems of Link 16 with regard to network flexibility and capacity. These problems are partly the result of not obtaining a SIAP, but the set of causes is much larger and includes basic technical shortcomings, the inconsistent implementation of a technical capability across different platforms, and the absence of necessary procedures. The root causes of the problem are numerous and include the following:9 Lack of a common time standard across the force, Poor tracking performance and inaccurate assignment of track quality, Inadequate and inconsistent navigation capability, Connectivity shortfalls, Failure to achieve a common geodetic coordinate frame, Differences in correlation/decorrelation algorithms, Differences in automated identification processing, Limited and inconsistent implementation of message standards, Shortfalls in joint tactics, techniques, and procedures, and Difficulties in network design and management. To confront the problem, the JROC directed in March 2000 that a SIAP system engineering office be formed.10 The SIAP system engineer is responsible for the systems engineering necessary to develop recommendations for systems and system components that collectively provide the ability to build and maintain a SIAP capability. By JROC direction, the Navy will provide the lead system engineer, the Air Force will provide the deputy lead engineer, and the Army will serve as acquisition executive. The SIAP system engineer has emphasized the importance of establishing 8 Joint Theater and Air and Missile Defense/Combat Identification Division (J85). 2000. Theater Air and Missile Defense (TAMD) Capstone Requirements Document (CRD) (U), Draft, U.S. Joint Forces Command, Norfolk, Va., June 15 (Classified). 9 Wilson, CAPT Jeffery W., USN, “Single Integrated Air Picture (SIAP) System Engineering,” briefing to the committee on August 30, 2000. 10 While the committee was not briefed on the program, it should be noted that the Family of Interoperable Operational Pictures (FIOP) program being developed in the Office of the Undersecretary of Defense (Acquisition, Technology and Logistics) is addressing issues related to the SIAP effort.

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Page 88 the necessary system engineering process and not just isolated improvements. Thus far, the office has identified candidate solutions to address the root causes noted above. Near-term emphasis will be placed on engineering and recommending SIAP-related improvements to fielded systems—in particular, identifying fixes to the joint data network (JDN). The JDN is the network formed from tactical data links, which in the future will be dominated by Link 16 for U.S. forces (but will also contain Link 22 for NATO forces).11 The SIAP System Engineering Office was created to meet a critical need, and its activities thus far appear well directed. The committee believes that the Navy should support the activities of this office and monitor them to make sure they are meeting naval needs. The committee further believes that the SIAP system engineer should take an aggressive stance in promoting the development of modern alternatives that would eventually replace the current tactical data links. 3.3.6 Cooperative Engagement Capability 3.3.6.1 Planned Capability CEC combines measurement-level data from multiple radars and other available sensors in near real time to form a composite track picture. The Navy's intent is to deploy CEC widely—on cruisers, carriers, some destroyers, amphibious ships, and surveillance aircraft.12 Initial focus is on air defense (primarily ship self-defense against cruise missiles), but later developments will address ballistic missile defense. The composite track picture provides each CEC participant with a better track picture than that participant could generate alone. For example, if a target is dropped by one radar, other radars can fill in, and target location can be determined more accurately by combining observations from multiple sensors. Furthermore, each participant has a larger battlespace picture, one that is produced by the combined coverage of all the sensors. This larger coverage will allow a given participant to launch its defensive missiles before its radar acquires a target—the so-called engage-on-remote and forward-pass concepts. The heart of the CEC system is the cooperative engagement processor (CEP) and the data distribution system (DDS). The CEP located on each platform correlates all the sensor input to that platform to form the composite picture. The DDS effects the high-bandwidth radar data distribution among the partici- 11 See CJCSM 3115.01 for more discussion of the JDN. Joint Staff. 2000. Joint Data Network (JDN) Operations, CJCSM 3115.01, The Pentagon, Washington, D.C., September 1. 12 There are some funding difficulties, however. The Navy's POM-02 budget submission dropped funding for installing CEC on existing E-2C aircraft and included it only for new E-2Cs. Existing E-2Cs comprise the bulk of the planned E-2C force.

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Page 89 pants. A prioritization scheme has been developed to send the most relevant data to each participant within the limits of the available bandwidth. Control of defensive missiles being fired using CEC data lies outside of CEC (in the C&D module in Figure 3.9 ). Thus, CEC does not form a complete BMC3 system, nor was it intended to; loosely speaking, it is a distributed sensor system. Over the last half-dozen years or so the CEC components have been upgraded and modernized, taking advantage of advances in computer and electronics technology and making increased use of commercial components. The production of CEC components began in 1998 at a low rate. Currently, CEC version 2.1 is undergoing large-scale, at-sea testing (the so-called Underway series).13 Operational evaluation is planned for the spring of 2001. Version 2.1 will provide an air-defense capability; ballistic missile defense capability is planned for version 2.2. 3.3.6.2 Possible Extensions In a CEC system, large amounts of data are transferred on a point-to-point basis between nodes, so scalability is an issue—that is, whether adequate amounts of data can be transferred as additional nodes are added to the system. This is one of the issues that will be addressed, at least for modest-size configurations, in the Underway tests. Furthermore, a new concept, the tactical component network (TCN), has been proposed that claims much more efficient data transfer. If this capability were realized, it could mitigate any scalability problems or even—possibly—allow for reduced bandwidth connections. The Navy is planning to investigate TCN and will outfit two cruisers with the capability. At this time, however, the eventual utility of TCN cannot be reliably predicted. The original concept for CEC was to enhance ship self-defense in carrier battle groups. Additional uses are being considered and warrant review here. The principal question is whether the extensive CEC capabilities are needed for these additional uses or whether lesser (and presumably less expensive) capabilities would suffice. CEC is being planned for use in naval ballistic missile defense and is also being considered for joint theater ballistic missile defense. However, a ballistic missile track picture is much easier to obtain than a low-altitude cruise missile picture.14 The question is thus whether the exchange of 13 For example, Underway 10, conducted in September 2000, involved six CEC-equipped ships (1 CVN, 4 CGs, and 1 LHD), two CEC-equipped aircraft (an E-2C and P-3), and three CEC land sites. BQM-34 drones were used as surrogates for cruise missile targets. 14 In cruise missile defense, the target can maneuver and present rapidly changing RCS to radar. This results in dropouts of target tracks and stresses track initiation algorithms. Ballistic missiles generally follow a Newtonian trajectory.

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Page 90 track data over an improved tactical data link capability, as could possibly be realized through the SIAP program, would be adequate. CEC is also being proposed for uses where there would be little overlap in coverage between sensors. For example, an advanced concept technology demonstration is exploring coupling Aegis and Patriot via CEC for low-altitude cruise missile defense. The main benefit of CEC appears to be that it provides a composite track picture from overlapping sensor coverage, in which instance it is valuable for exchanging measurement-level data. When the coverage regions do not overlap significantly, it could suffice just to send track data, which could be done via a (possibly enhanced) tactical data link.15 The committee believes CEC can provide a valuable capability for ship self-defense and overland cruise missile defense if adequate overland sensors are available in the latter case. The committee does not have adequate information to take a position on the issues of extended use noted in the last two paragraphs. However, it believes that the Department of the Navy and the joint community should conduct adequate analyses to resolve these issues if they have not already done so. No such analyses were apparent in the briefings received by the committee. Rather, it appeared that since CEC was an existing capability, at least in prototype form, it was being extended to new uses without an adequate analysis of the alternatives and trade-offs involved. The advantages of using an enhanced tactical data link capability could be reduced cost and greater operational flexibility in passing the data, since tactical data link terminals will be more widely deployed. Furthermore, just as one should guard against locking into legacy Link 16 technology, one should also be cautious about locking into CEC technology. While CEC is highly capable, it must be kept in mind that it is based on an architecture first designed in the 1980s. 3.3.7 Area Air Defense Commander Module Joint doctrine calls for the establishment of an AADC to oversee air defense operations under a joint task force commander.16 The AADC module is a display capability and associated tools for use at the AADC (i.e., operational) level as well as at the tactical level. While Navy doctrine does not have an exact analogue of the AADC, the AADC module is intended for use in naval as well as joint operations. 15 There could be an advantage to netting multiple Patriot systems together using CEC if there was significant coverage overlap among the Patriot radars. 16 Ross, Lt Gen Walter K., USAF, Director, Joint Staff. 1996. Doctrine for Joint Theater Missile Defense, Joint Publication 3-01.5, The Pentagon, Washington, D.C., Available online at <http://www/dtic.mil/doctrine/jel/new_pubs/jp3_0l_5.pdf>.

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Page 91 The AADC module display shows air and ballistic missile defense assets, hostile forces, and neutral entities—all depicted as the real objects in a three-dimensional representation instead of in terms of some abstract symbology. This information is updated through information feeds such as Link 16. In joint operations, the joint force air component commander (JFACC) air-space control authority (ACA) prepares the airspace control order (ACO) that determines the partitioning of the airspace to deconflict the various offensive and defensive assets that will be operating in it. The AADC module provides a three-dimensional rendering of this partitioning. In addition, it displays such operational parameters as the coverage areas of surveillance systems and the range of weapon systems. It also supports collaborative planning by providing a visual teleconferencing capability. The AADC supports both planning and execution. Its displays and tools allow the initial positioning of air defense forces to be determined much more rapidly than with the conventional manual procedures. However, the material presented to the committee on the AADC module did not appear to indicate that the operational concept for the interaction between the AADC and the JFACC had been fully worked out—for example, the concept for the coordination and airspace deconfliction of offensive and defensive operations, which is necessary to take full advantage of the AADC module's capability. Similarly, further development of the operational concepts for joint ballistic missile defense also appears to be required. In execution, the AADC module's display and tools allow for the near-real-time tasking and redirection of defensive assets. This capability should aid tactical command and control of defensive operations significantly. The committee did not, however, receive adequate information to be able to assess the sufficiency of the AADC module's battle management tools. That is, while there is significant capability in the module now, further automated battle management aids could be desirable to cope with complex, multitarget situations. There is an important cautionary note pertaining to accuracy: The AADC module's display is very realistic. Such displays can lead observers to believe that is how the real situation is, when in fact there can be errors in location, identification, and completeness in the data input to the display. Operators should guard against taking the displays more literally than is warranted. Means should be sought for depicting the uncertainties in the AADC displays. Furthermore, safeguards against the engagement of neutral targets—such as the inadvertent shooting down of an Iranian Airbus in the Gulf many years ago—must be incorporated in the system. For example, as currently envisaged, the AADC makes no use of the Official Airline Guide, and it has no links to civilian air traffic control. AADC prototype modules have been installed on the command ship USS Mount Whitney and the cruiser USS Shiloh. The prototype module on the Shiloh was used in the rim of the Pacific (RIMPAC) exercises in the summer of 2000. Its use was apparently well received. Further testing of the AADC module is

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Page 92 planned, for example in the Abraham Lincoln battle group, and initial operational capability (IOC) is planned for FY06. In summary, the AADC module should provide a valuable capability supporting those management/control functions shown on the right-hand side of Figure 3.5, above, as well as the non-real-time planning function. However, as noted, further development of the operational concepts necessary to execute these functions could be warranted, and serious consideration needs to be given to the representation of uncertainty in the battlespace display. 3.3.8 BMC3 Summary The BMC3 discussion above, augmented by the material in Appendix C, may be summarized in terms of a set of conclusions. Overall, the committee found that BMC3 concepts and technical capabilities require significant rethinking and development to meet missile defense needs. More specifically, the committee concluded as follows: Operational concepts and the associated technical capabilities must be able to support highly adaptable missile defense force configurations; the current approach—thinking of prescribed configurations—is not adequate. Experience has shown that force components must be pulled together in unplanned ways and unanticipated assets often added in. What is required is a technical basis that makes this jury-rigging readily accomplishable—namely, a network-centric architecture that allows the easy interconnection of assets and enables users to readily identify information and get it from any source. Current missile defense BMC3 architectures are not of this type. Wide-area missile defense puts an increased premium on BMC3, to which current Department of the Navy efforts are not paying adequate attention. Furthermore, as the threat becomes more stressing, even local defense will require more emphasis on BMC3 to increase its horizon against threats. For example, in wide-area mission overland cruise missile defense, naval forces lack effective surveillance capability and would need the capability provided by a platform such as the AWACS or, perhaps, a group of UAVs. Crossing Service lines like this means that the appropriate technical and procedural capabilities must be in place; the committee saw no evidence that these requirements were being addressed for overland cruise missile defense. Ship self-defense is an example of local defense where the threat is expected to increase in terms of both numbers and reduced detectability. Interfacing with an AWACS, for example, would increase the horizon, allowing the defense more time to meet the threat. The general point to be drawn from this is that effective future theater missile defense could require not only the physical distribution of sensing, control, and shooting assets, but also their distribution across Services. This would entail a major cultural change for traditional Service operations.

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Page 93 While both Link 16 and CEC provide valuable capabilities, neither is likely to be evolved far enough to provide the capability needed for flexible connectivity. Link 16 does not allow for the rapid incorporation of unplanned platforms or unanticipated information sources into its network. Enhancements are planned, and they will be useful for near-term improvements to the network, but there are limits to these improvements given the very dated technology and architecture upon which Link 16 is built. CEC was designed to be a distributed radar, and it is quite effective in that sense. However, while it does have a high bandwidth, it was not designed to be a multipurpose communication system easily accommodating the inclusion of nodes not designed to its specialized interface specifications. Newly emerging commercial wireless technology can be leveraged to meet missile defense communications needs. Commercial technology is providing multi-megabit-per-second wireless communications and has developed quality-of-service capabilities and some information assurance capabilities. Although antijam capability is typically not a feature of commercial technology, that technology should nonetheless be a good starting point for adding in this capability. Current improvement efforts face the coupled problems of limited bandwidth and poor battlespace control capability. Solving the bandwidth problem disentangles the two problems and allows focusing on battlespace control. Determining an accurate battlespace picture and coordinating the assets in it remains a difficult problem that requires much more attention. Current efforts to improve battlespace coordination must be continued and augmented with more advanced research. Increased bandwidth will allow greater data exchange, which should allow better correlation of detections, but significant improvements beyond that will still be required. Programs such as the SIAP and FIOP are necessary, and even more advanced research programs are necessary. Areas of research include the decentralized management of resources and the management and presentation of uncertainty.