You don’t leave your military in a nation after the war is over

Yes you do.

Sovereign nations don’t allow that.

The occupied usually surrender territorial control, and all the allied nations stayed in Germany for a number a years... hence the whole east west divide.

Anyways, I get to say what I meant by Nation Building in my comment. I don't know what you're on about. Are you trying to point out that the US is corrupt? Because buddy, that's already apparent to most people.