For what it’s worth, I agree with SECDEF Gates’ rebuttal via the New York Times; deploying sea-based SM-3 interceptors can happen faster than the previously-planned ground-based interceptor, and the SM-3 has a better track record than any other BMD system being tested and fielded today. Even the future plan to have ground-based SM-3s has a certain merit.
But there are some large caveats and potential issues. First and foremost is the capabilities of the United States Navy, specifically the guided missile cruiser (CG) and destroyer (DDG) platforms that will be the mainstay of this plan.
There are 22 active Ticonderoga-class CGs, and 55 active Arleigh Burke-class DDGs in the USN inventory, all of whom carry the enormously capable Aegis Combat System. Right now USN has upgraded 3 cruisers and 15 destroyers to BMD capability, with three more still on the books; that’s 21 total Aegis BMD platforms to patrol the world’s seas.
Obviously all 21 ships are not out at sea at any given moment; in a standard USN single-crew rotation, a surface warship will spend 12 to 18 months training and performing maintenance on their vessel to prepare it for deployment. Then the crew takes their ship on a 6-month deployment, at the end of which they return to home port and the cycle begins anew. The actual amount of time it takes a ship to begin and end that cycle also depends on how far away its patrol station is, whether it is leaving from the East or West Coast, and how many intermediate stops it makes. Generally speaking it takes somewhere between three and six weeks to arrive on station.
With those limitations in mind, USN thus requires a force of six surface combatants to keep a single vessel on-station at all times in Central Command’s AOR—or a rotation ratio of 6 to 1. For European Command or Pacific Command, the ratio is 4.5 to 1. If you factor these in to the current Aegis BMD fleet size, you will realise that only four Aegis BMD ships will be on-station at any given time—one or two in European and Central Commands, and two in Pacific Command. The others will be back at home port working up for the next deployment, or steaming to and from their assigned station. And that’s it; you’ve maxed out the deployment capabilities of your Aegis BMD fleet.
Now USN has experimented with Blue/Gold dual crews (such as those used on its SSBNs and SSGNs), and is planning to use multi-crew rotations for its Littoral Combat Ships, thus increasing the amount of time they spend at sea. (For an in-depth analysis of USN multi-crew rotations, see the Congressional Budget Office document “Crew Rotation in the Navy: The Long-Term Effect on Forward Presence“, October 2007.) Such a solution could be implemented on Aegis BMD ships (if not the entire surface combatant fleet at large) to help offset the limited number of vessels. But even this is not going to give you the sort of constant all-aspect coverage US and allied policymakers—and their publics!—will want from a BMD system. To have a really effective deterrent, you need to increase the number of BMD-capable vessels.
If we are (as the SecDef has previously indicated) living in an era of flat, constrained defence budgets, then either BMD is going to remain a niche capability confined to one quarter of the CG/DDG fleet, or the Administration is going to have to find creative ways of funding BMD upgrades for more ships.
One other concern, too, is that all of Europe’s missile defence eggs will be riding on a single weapon system. Should opposing forces come up with a cheap and effective way of jamming or defeating the redoubtable Standard SM-3 (besides sheer volume of missiles), then they will have defeated the totality of this administration’s planned European BMD deployment. There is a certain value in having multiple capabilities on multiple platforms, but for now Europe will have to hope the SM-3 will remain as effective as it appears to be today.
The other downer is countering a CG/DDG. To degrade the effectiveness of a land-based facility you can either 1) degrade or destroy the radar, 2) degrade or destroy the interceptors or 3) oversaturate the BMD system with more targets than it can intercept. None of these methods are particularly cheap. But to degrade the effectiveness of Aegis BMD you really only need one thing: a quiet diesel-electric sub. Those aren’t too hard to come by.