The post-Bush missile defense debate is already underway inside the Beltway and the Pentagon. One of the primary focuses is what role the U.S. Navy will play in the wake of their highly successful Aegis shots.
The bulk of missile defense literature published by Naval officers and experts treats the Navy's role in missile defense in largely theater and regional roles. This is consistent with the Navy's traditional contribution to U.S. defense strategy -- forward defense of our allies, bases and interests on the periphery of Asia and in the north Atlantic, as well as sea lane protection and maritime security and superiority. And for this purpose, the Navy has adopted an eminently suitable weapons system -- the mature, already deployed Aegis fleet air defense system that thanks to modifications as well as cooperative programs with Japan and other allies has evolved into an impressive missile defense capability.
Sea-based missile defenses may offer some advantages over investments in additional permanent fixed sites, especially for the forward defense of allies in Europe or other theaters. Their mobility enables them to be more responsive to unexpected shifts in adversary threat developments, and predictably unpredictable political shifts. And because they deploy with the fleet, both helping to provide and receiving the benefits of defense in depth, they are possibly less vulnerable even when they have to operate close inshore than static land-based defense sites.
One imperative the Navy faces in assuming a missile defense role is that it needs its assets to maintain their other duties like air defense and anti-submarine warfare. This is particularly true as the fleet has fallen below 300 ships. Consequently, as the Navy incorporates missile defense into its missions, it is looking to avoid situations where its ships must stand "picket duty" indefinitely in a specific locale, becoming either "sitting ducks" or requiring other scarce fleet assets to be diverted to their defense. In principle, therefore, the "longer-legged" and more flexible the Navy's missile interceptor assets the greater their ability to engage potential enemy targets and the better for sea-control operations.
It could be strategically and politically astute for the Navy to build on its theater missile defense capabilities and assume a forward role in national missile defense. This, however, would require the Navy to deploy interceptors effective against both theater missile threats and future ICBM threats against the U.S. homeland. Interceptors flexible enough and with enough capability to address such a long-range threat in boost, ascent, and mid-course phases of flight would permit ships with missile defense missions from being able to perform these duties from a wider ocean area consistent with the Navy's imperative to keep them "with the fleet."
The Navy should consider exploring other complementary interceptor options if it aims to be effective at more than regional/theater missile defense around the Asian and European perimeter. The Kinetic Energy Interceptor could offer one such capability. It is probably too large to be accommodated aboard existing destroyers and cruisers without extensive and expensive modifications. But there are other hull options that might be worth exploring -- converted Trident submarines, amphibious hulls, and our next generation cruiser, CGX.
This option would permit the Navy to deploy an effective interceptor against threats to the continental U.S. and against regional missile threats where inland launch points present stand-off distances beyond those at which the Standard Missile might not be able to reach.
The whole theater/strategic dichotomy in missile defenses is an artifact of the Anti-Ballistic Missile (ABM) Treaty era, which is now over. This archaic distinction made it possible for us (and the Soviets) to continue work on some missile defense technologies that we agreed were useful for the protection of forward deployed forces without posing any challenge to nuclear deterrent forces. But both the advance of technology and the renunciation of the ABM Treaty have made this distinction something between useless and harmful.
In today's context, it makes far more sense to think in terms of a portfolio of missile defense capabilities that can range from theater to intercontinental, from boost to terminal, and potentially handle rogue states as well as emerging great powers like China and Russia.