programs, may be principally intended to balance, deter, or threaten rival regional powers. In such situations the United States may elect neutrality, good offices to resolve differences and limit arms races, or tilting toward the party less likely at some point to collide with U.S. interests. As regards the last of these options, the United States will need to take care not to become so deeply tied to one of the parties in a two-party regional rivalry that it loses room for maneuver or encourages that party to assume the United States will support it militarily in a possible war. (The United States may choose to do so but ordinarily should not give so much support in advance that its preferred party starts the war itself. This consideration should also limit the types and quantities of military equipment the United States might supply to the preferred party.)
19. A tentative conclusion: In the post-Cold War world, "existential deterrence," i.e., the sheer weight of American power, will not prevent many conflicts nor even threats or actions against American interests. If a threat is perceived, more directly applicable and visible force will be required to deter and contain it. It will be desirable to undertake such countermeasures in association with other states, but this may often be difficult because of differing threat assessments and judgments as to the most effective means to be used. There will be numerous aspiring powers over time, including some with at least a rudimentary ability to injure the continental United States. In the latter case, a Cold War-type of deterrence, combined with defenses and containment strategies, may be the most desirable option. When aspiring powers are regional rivals of each other, it is in the U.S. interest to help prevent war; in so doing the United States should not tilt so far toward one of the parties as to run the risk of getting dragged in or of encouraging that party to start a war.