Yglesias points out this report from the Center for American Progress on sea-based ballistic missile defense, in which Andrew Grotto and Rebecca Grant argue for continued funding of research and development into AEGIS based ballistic missile defense systems. I can’t really disagree with that conclusion, but I do think that they overstate their case; sea-based ballistic missile defense is nice on the margins, but except in a very few tactical situations, it is unlikely to change the course of any imaginable conflict.
On the plus side, sea-based ballistic missile defense avoids certain of the problems of land based systems. Land based systems (such as those being installed in Poland and the Czech Republic) carry with them significant political costs, and are vulnerable to political shifts in the host countries. In their current configuration, land based systems are also dependent on a certain constellation of threat. If, for example, we spend a tremendous amount of money building an anti-Iran system in Poland, then the Iranian government collapses and is replaced by a friendly regime the next day, we have wasted a lot of money (this assumes the entire point of the system isn’t to antagonize Russia, which may not be reasonable). A ship-borne missile system can just steam to wherever the threat is, be it near Taiwan, North Korea, Iran, Venezuela, or the target du jour.
Sea-based systems can also provide some protection against what may be the most significant threat that conventional armed ballistic missiles pose, which involves attacks on aircraft carriers and assault carriers. As I’ve suggested before, accurate, terminally guided ballistic missiles could give a US supercarrier a very bad day. Such missiles are beyond the capabilities of Iran or North Korea (for the time being) and possibly even of China and Russia in certain circumstances, but if the various problems can be worked out, they could be very threatening indeed. Carrier battle groups with BMD capable AEGIS ships would provide some (although not complete) protection against this kind of attack.
However, naval BMD doesn’t solve the basic problem of ballistic missile defense, which remains the disjuncture between expected costs and expected benefits. We’re familiar with the difficulties of defense against nuclear armed ballistic missiles; unless the BMD shield can be expected to operate at 100% effectiveness, the threat of nuclear attack will deter the United States from whatever action it would like to engage in. Put simply, a shield that’s 95% effective will result, in average, in one destroyed city per twenty missiles, and a fifty percent chance of a destroyed city per ten missiles (try it sometime with a 20-sided die). These are odds that no rational leader will accept, which means that we end up relying on our own nuclear deterrent, which puts us back at square one. Any adversary capable of putting nuclear weapons on missiles can still “hold us hostage” no matter how many AEGIS ships we have off its coast; indeed, if it’s really interested in holding us hostage, the adversary can come up with alternative means of delivering the weapons, such as by submarine.
But surely naval BMD could help reduce the threat of conventional missile attacks? Of course, but this threat is almost certainly overblown. Worst case scenario, China could launch a thousand missiles at Taiwan, and possibly do extensive damage to military and civilian facilities. Would this, in itself, bring about a Taiwanese surrender (replace Taiwan with Georgia if you prefer)? If it did, it would represent a remarkably ahistorical outcome. We know, not just from World War II but also from Rolling Thunder, Desert Storm, and Kosovo, that civilian populations are remarkably resilient to the threat of terror bombing, and that industrial economies do not collapse easily. Military targets, properly prepared and hardened, are also quite resilient to bombing (with the above noted exception for aircraft carriers). Thus, when Grotto and Grant write
Iran and North Korea’s missiles may not be highly accurate or heavily armed, but their effects would be dangerous nonetheless, terrorizing civilian and military populations and/or potentially disrupting U.S. military operations
I’m inclined to think “Really? How?” First, inaccurate and lightly armed missiles will not, in fact, pose a threat to US military operations. Iraqi Scuds killed a couple dozen US soldiers in the First Gulf War, but they had no effect whatsoever on military operations. The much vaunted Iraqi Scud assault on Israel resulted in more deaths from heart attacks than from blast. Ballistic missile attacks can, like any air assault, produce dislocation and chaos, but this effect is temporary, and largely unproductive in terms of costs and benefits (it costs more to buy and launch a missile that the damage you can expect the missile to inflict). We have been forced to learn, over and over again, that complex societies do not crumble under temporary, small scale air attack; they invariably adjust, and life goes on. Since ballistic missiles are a remarkably inefficient way of delivering conventional payloads (although sometimes the only way), I’m just not convinced that they pose a dire threat to US military operations or national security.
That said, it’s better to have x-1 missiles hit a target than x missiles. To the extent that developing ballistic missile defense capability for AEGIS ships can reduce the number of hostile missiles that will hit the United States, its military installations, and its allies, continuing development (and expanding deployment) of the system makes sense. We shouldn’t, however, fool ourselves into thinking that sea-based BMD is some kind of game changer, or that it prevents rogue states from “holding us hostage”.