Wrong.
If the US did not currently have an empire, we would have a military about 1/10th the size of the one we have not, that uses about 75% of our national budget.
If the US did not currently have an empire, we would not have invaded Vietnam, Panama, Grenada, Iraq, Afghanistan, Libya, Syria, etc., and we control Palestine, Israel, Egypt, Saudi Arabia, NATO, the UN, etc.
The fact we do not do it as blatantly as the ancient Romans did, does not mean our economic bribes, extortion, monopolies, etc., are not an illegal empire.