[Manthink]

US is the only one which does not  have empires compared to the past

The word "empire" is a definition of a power entity, not an item to "have". E.g. Japan and Britain were once called "empire", never called to "have empires".

Just that today, this word got replaced by the "Superpower"...which interestingly was invented an American in 1944...1 year before the end of WW2.