Also up till a couple of years ago, strategic arms treaties meant that US inspectors were looking at all those warheads and missiles regularly. I am prepared to accept they might notice a fault that would turn a 1Mt warhead into a 50kt warhead and 'forget' to tell the Russians but if there was the slightest chance they were in dangerous shape, you bet they'd flag that up the chain.

Betting the Russian arsenal is in as poor shape as the rest of the military is a dumb idea.