Fast GBIs could be preferred when water permitted survivable access. The advantages of the concepts are largely complementary. It is too early to say which would be the best choice technically. Summary and conclusion . Current defenses should be adequate for projected unitary threats, but could be offset by multiple, chemical, biological, nuclear, maneuvering, and early deployed weapons, which are at roughly the same level of technology.
Additional development is required.
Boost phase detection and interception have promise, but require development. Airborne lasers are more developed than space lasers, but have more serious propagation issues. Space based lasers interceptors are not optimal for theater launches. Fast ground based interceptors could be for engagements where the launchers could be based survivably and detection and command provided promptly. At current development rates, it is unlikely that any will be an effective deterrent on the time scale of the evolving threats.