Prominent missile defense advocate describes this system openly as a prerequisite for successful future U.S. interventions that would otherwise be deterred.
From similar reasons he favors mobile sea-based missile defense, not the one deployed on the land.

Why the best offense is a good missile defense.

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In fact, the strategic logic of missile defense runs entirely counter to the claims of isolationist champions and liberal critics alike. The real rationale for missile defense is that without it an adversary armed with long-range missiles can, as Robert Joseph, President Bush's counterproliferation specialist at the National Security Council (NSC), argues, "hold American and allied cities hostage and thereby deter us from intervention." Or, as a recent RAND study on missile defense puts it, "[B]allistic missile defense is not simply a shield but an enabler of U.S. action." In other words, missile defense is about preserving America's ability to wield power abroad. It's not about defense. It's about offense. And that's exactly why we need it.

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The real argument for missile defense is that we need it to prevent adversaries from deterring us from the kind of interventions that liberals like Reich, even more than conservatives, spent the 1990s championing. Oddly enough, foreign critics, who carp that missile defense will cement U.S. hegemony and make Americans "masters of the world," grasp its rationale better than critics here at home. Missile defense, China's ambassador to the U.N. Conference on Disarmament complained recently, would grant the United States "absolute freedom in using or threatening to use force in international relations." He's right.

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... water covers 70 percent of the Earth's surface. This simple fact has enormous strategic and technical implications. First, it offers a way around the problem of decoys and multiple warheads. Missile interceptors stationed on U.S. ships, which would patrol the coasts of rogue states, could shoot down missiles in their initial boost phase - that is, before they could deploy countermeasures and while their engines were still emitting an easily detectable plume of flame. Trying to destroy a missile as it lifts off, as opposed to when it's about to land on you, makes sense on several counts. Aside from solving the countermeasure dilemma, it's a lot easier to hit. As anyone who has seen a televised space launch knows, rockets travel relatively slowly during their initial ascent - much more slowly than when they streak back to Earth.

Equally important, a sea-based defense would offer the United States more than one opportunity to bring down an incoming missile. And, as physicist Richard Garwin points out, "It is much easier to put a lid on North Korea, a country the size of Mississippi, than it is to put an umbrella over the whole of the United States." If a missile did get through the first line of defense--or if it was launched from, say, China's vast interior, which no boost-phase interceptor could reach in time--American forces could conceivably have as many shots at it as there were ships stationed along the weapon's trajectory to the United States.

... The mere fact that missile defense ships could be deployed to war zones as part of larger naval armadas gives them an immediately recognizable offensive dimension. Like aircraft carriers, such ships could project power in ways no concrete slab in Alaska could. If, as the Bush team insists, the strategic rationale for missile defense really is an internationalist one (that means more U.S. engagement-encroachment in the world affairs - note of the No to Bases initiative), then a sea-based system has all the advantages. 


Source (American): Kaplan, Lawrence F. Offensive Line. The New Republic, March 12, 2001, Vol. 224, Issue 11, p20-25