This is obviously false, we have hanged or imprisoned Nazis for committing war crimes and they never signed up to any treaty about war crimes.

Also ICC has issues a warrant for arrest of Putin, and he never signed up to ICC either.

Can’t have it both ways

We fought and won a war against the Nazis. imposing one's law on another country can be done by that method of course.

Putin doesn't give two fucks what the ICC says. As I pointed out in another comment, issuing warrants that one cannot enforce is worse than useless.

None of these things affect the accuracy of my comment.