ICBM missile solo, not something you really want to blow up, but it would be cool if you could eliminate it within minutes should it start to pose a risk.
How would the Russians react? Would they launch extra nukes just to be "safe"? Maybe we should build a weapon that ~enhances the yield of their nukes, so that they figure sending one is enough!
Your username suggests that, had you been born 10 years earlier, you would have already been thinking about things like that for several years when the Berlin wall came down. But instead, you were 9 and the world has rarely been at risk of full-scale nuclear war for you.
The questions that you seem to be posing sarcastically were really, truly discussed seriously from 1959 through 1989.