Well, when it happens to the level that it has under Trump, that country is in big trouble also. But noone (and I mean noone) has damaged a democratic nation as badly as Trump. There are a lot of contenders, but they all miss the mark by quite a bit.
Russia was hardly a demoncratic nation. Thatcher is close, but she is not even close to the damage that Trump has done to America. The UK recovered, the U.S. will not.