[Symmetry]

Being a democracy or not doesn't really have anything to do with being an empire, generally you have an empire when you have a state substantially composed of multiple nations. But generally with imperial democracies its only one nation that is a democracy, like in the British Empire where Britain, a democracy, ruled a huge colonial empire.

If you really squint hard you could argue that the rest of NATO are military tribute states giving soldiers to the US empire but that's a very strained interpretation. Japan is currently pretty dependent on US military protection but that doesn't seem to have turned into economic exploitation. Certainly American efforts to get Japan to open up to more US exports isn't something Japan has just rolled over on.

But the current international system does have the US at its center and colloquially people call this the American Empire, and we know what they're talking about even if it isn't really an empire.