When I was talking about offensive systems, I was talking about the very negative international security and arms control consequences of pursuing missile defences. I'd like to make the point that in my view it's not inconsistent at all to argue that the BMD system, as it's currently configured, doesn't work, but that prudent Russian and Chinese defence planners must hedge against the possibility that it might someday work. That's what defence planning is all about.
I'm not advocating building a massive offensive system, but I would note that among the nine declared nuclear weapon states, we actually have a rather significant modernization program going on. What I was arguing was that the whole logic during the Cold War when the Soviet Union and the United States were facing off at each other—and I argue it holds true today—was that you don't invest in missile defences because they are so easily.... Missile defences are so hard to prevail; they have to be 100% accurate so that nothing can get through. As for offensive systems, the famous Nitze doctrine was that they're “cost-effective”.
The question of cost-effectiveness is at the margins. It will always be cheaper to build more offensive systems. If you go down the road of missile defence, even if you have a somewhat reliable system, which the current one is not, you're pushing on the other side, those who are concerned—Russia and China in particular—to hedge their bets by building more offensive systems and by building more manoeuvrable systems.
Part of the deal in the Cold War was not only that there were no missile defence systems except a very restricted one, but also, there was an agreement to ban the MIRVs, that one missile system that has many independently manoeuvrable warheads. On that, too, the Bush administration gave up when they abandoned the ABM treaty, and now China is pursuing that.
The argument is that there is a lot of evidence of the negative consequences in arms control terms of going down this road and very little on the other side in terms of a positive benefit of this system.