I always thought that China/Russia/etc would think that those old bunkers were where America’s rich and famous and influential were holed up and so, therefore, nuke the hell out of it.
Whats the one place that your enemy wouldnt move? A known target like these bunkers.
Your enemy knows you know that so you might just hide something important there.
Which, of course, means they have to hit it just to make sure you didnt.