U.S. missile defenses use kinetic energy, not explosives, to destroy enemy missiles—the “kill vehicle” simply slams into the target. The kill vehicle carries no explosives, which means the kill vehicles that don’t hit the target simply continue on their merry way, re-entering the atmosphere and, for the most part, burning up. For scenarios in which the Alaska site shoots at a North Korean missile, the kill vehicles should mostly re-enter the atmosphere over Russia.
You might feel a twinge of unease, thinking about a large number of U.S. missiles streaking into Mother Russia, lighting up Moscow’s early warning system before burning up. The Russians would know we aren’t attacking them, right? I mean, they wouldn’t do something crazy like get out the Cheget, their version of the nuclear football used to launch a nuclear retaliation, would they?
Well, they might.