Most experts seems to think that interception is basically impossible to do reliably with current technology, even before you get into the question of counterme

Most experts seems to think that interception is basically impossible to do reliably with current technology, even before you get into the question of countermeasures, and that with the sheer quantity of warheads, it's basically a given that a large majority would land. Whether the entire six thousand or so warheads would explode, or the one-and-a-half thousand deployed missiles would actually reach their targets is anyone's guess. However, bearing in mind that even one nuclear explosion is capable of killing about a million people, if detonated in an urban center, it really just takes a comparative handful of working weapons, say 1-2%, to kill as many people outright, in the initial explosions, as the number that died in the whole of WW2[0]. [0]: 1-2% of 6000 = 60-120, 60 to 120 * 1million = 60 to 120 million, around the same ballpark as deaths in WW2. That's obviously just the initial direct deaths, there would obviously be many more (an order of magnitude, at least) from follow-on effects. And this is ridiculously low-balling the estimate for how many of the warheads would be delivered to target: a more realistic estimate would be like, 90%.