What’s the reason the U.S. wants missile defense? Same reason as Israel, Taiwan,
Bahrain, the Saudis, the Gulf Cooperation Council states, South Korea, and everyone else: it can contribute to assured survivability.
As your mother may have told you, an ounce of prevention can be worth a pound of cure.
While much of the arms control industry peculiarly advocates for an international balance of power that can only be described as mutual vulnerability, missile defense helps nations move away from that nonsensical position.
So the Russians, seeing that U.S.-developed missile defense works now and that it is likely to work better in the future, have been whining about the topic unendingly.
The latest whine came at the announcement that the U.S. and Romania had agreed upon a Romanian siting location for U.S. provided missile defense interceptors.
Russia immediately complained that the interceptors in Romania could undermine its nuclear deterrent, and said the step ignored commitments made by the United States that Russia would have a role in decision-making.
Stand fast Ivan: I’ll call the waa-mbulance.
The Russian anti-missile defense script goes like this: offer to “partner” with the U.S. and NATO; whine; accuse the U.S. of changing its “agreement” (which is one of those shape-shifting nouns the Russians use to mean anything they like); threaten to deploy more nuclear weapons; try and get NATO/Europe to cave on the issue and/or to put pressure on the U.S.
The Russians have few plausible options to enhance their own national power so they’re playing this “soft power” fiddle as best they can.