Alex WellersteinVerified account

1. There are many ways to fake them out, 2. Existing systems only show partial success under idealized conditions, 3. Prob. of failure so high, and consequences associated with failure high, that confidence is not at all warranted.

To put it another way: If it comes down to our BMD systems needing to work to avert catastrophe, then we're really in a bad place. That doesn't mean they shouldn't work on BMD (though there are other reasons why that might be an issue, like destabilization w/Russia), but

it does mean that they should not be used as a strong "crutch" in our discussions about deterrence, etc., or give policymakers (or citizens) the confidence to escalate situations.

I worry very much when I hear US officials declare how well BMD "works" and use that as essentially an argument for, say, preemptive strikes. Even a BMD supporter should not be eager to test if BMD works in the real world.

And in the long run, BMD systems — even ones that worked — will just encourage alternative means of delivery. Nuclear nations aren't just gonna say, "you got us, we give up!"

We are already seeing this with China and Russia (hypersonic, long range cruise, etc.), and there are low-tech approaches too (which are perhaps scarier than ballistic missiles, like smuggled weapons).

So if the goal is strategic stability, BMD is probably more undermining in both the short and long term than it is helpful. But that's a separate question from confidence in the systems as they exist today.