ing system performance and evaluating new initiatives before significant funding is committed. Cost-benefit analysis should be central to that capability.

•   In addition to terminating U.S. boost-phase missile defense systems, MDA should terminate the PTSS unless a more convincing case can be made for its efficacy for the mission that it is supposed to carry out.

•   PTSS provides no information that a combination of the SBIRS and the proposed suite of X-band radars with the interceptor sensors will not provide better and at lower cost both initially and over the life cycle. Moreover, as proposed, PTSS contributes little if anything to midcourse discrimination.

Major Recommendation 4: As a means to defend deployed U.S. forces and allies from short-, medium-, and intermediate-range ballistic missile threats, the Missile Defense Agency and the Services should continue investing in non-boost systems such as Aegis, THAAD, and PAC-3, with continued attention to architecture integration of sensors with shooters (sometimes referred to as an integrated battle command system, or IBCS), specifically to implement launch-on-remote (LOR) and engage-on-remote (EOR) firing doctrines.

•   EOR is essential for effective coverage of Europe from a small number—say, two or three—of interceptor sites.

•   Inputs to the IBCS already include those from DSP, SBIRS, and upgraded UHF early warning radars. Maximum use should be made of these data to relieve X-band radars of unnecessary volume or fan search functions, permitting them to concentrate radar resources on tracking and discrimination at the longer ranges permitted when the radars are properly cued to the targets. This involves little or no new investment. Data latency is a potential problem for the IBCS that should not be ignored.

Major Recommendation 5: As a means to provide adequate coverage for defense of the U.S. homeland against likely developments in North Korea and Iran over the next decade or two at an affordable and efficient 20-yr life-cycle cost, the Missile Defense Agency should implement an evolutionary approach to the GMD system, as recommended in this report.

•   Chapter 5 recommends an evolutionary path from the present GMD system to a system having substantially greater capability and a lower cost than a simple expansion of the present GMD system. The recommended path builds on existing developments and technologies working together to make a more effective system. The concepts are not new and have been well known for at least 40 years. Existing advances in optical and radar technology will enable its realization.

•   The evolutionary approach would employ smaller, lower cost, faster



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