I think there’s a limit to the utility of this kind of argument, regarding a new laser-based air defense system:
This all sort of leaves me wondering what problem this technology is a solution to. For the past twenty years every conflict the U.S. military has been involved with has involved overwhelming American air superiority. Finding better ways to shoot down enemy aircraft hasn’t been high on the priority list. But by the same token, the very dominance of American air power means that this would be very useful for America’s adversaries. Nobody we’re realistically going to fight could possibly build up a squadron of fighters to go toe-to-toe with the Air Force, but plane-killing lasers could be very useful. Obviously Boeing isn’t working on this technology in hopes of selling it to the Taliban, but my sense is that we should be hoping that we see relatively little progress on this sort of thing in years to come.
There are a few ways to think about this. There’s some space between “we need to buy a fleet of F-22s in order to counter future unforeseeable threats” and “advances in air defense technology are worth the investment.” For one, there’s a difference between construction of a specific platform and development of capabilities that may or may not be put into mass production. In ten years, I could see myself opposing a proposal to purchase a large number of air defense lasers; right now, I think it would be kind of nice to have the capability to think about the question in ten years. That the national security environment isn’t terribly predictable shouldn’t be an excuse to build every imaginable weapon, but it’s nevertheless nice to have some flexibility.
Second, while Yglesias makes an interesting point regarding the idea that improvement in anti-aircraft technology represents a net loss for the United States, I don’t think his (underspecified in any case) conclusion follows. For one, other countries understand the basic relationship between power projection and air defense technology as well as we do, and are already working on more capable systems. There’s no “air defense arms spiral,” because air defense system do not, after all, fight each other. US strike capabilities already give Russia, China, India and others a strong incentive to pursue advanced air defense technology, and I doubt very much that US air defense will matter very much. Moreover, there’s little reason to believe that eschewing air defense technological development will slow foreign innovation, as they already have plenty of reason to pursue advanced capabilities. If anything, the spiral is generated by improvements in US strike capacity.
Third, while it’s unlikely that the United States will, in the foreseeable future, have to defend a target from a swarm of fighter-bombers, it’s not so unlikely that we’ll have to defend against unmanned drones or cruise missiles. The development of cheap and effective drones is much more destabilizing, I think, than innovative development of air defense technology. Drones and cruise missiles give air strike capability to countries that can’t hope to win air superiority, as the relatively low cost of the platforms means that high losses become acceptable.
This is to say, then, that developing advanced air defense technology does not a) commit us to the purchase of any particular weapons system, b) provide cause for an arms race, c) provide a solution to a problem that is highly unlikely to arise.