The problem with the term 'empire' is its connotations, I think. People consider either the Roman-style notion of an all-encompassing military power, or the British-style colonies. When people refer to "US imperialism", they're usually referring to the forced imposition of ideas and ideals, the *sometimes extreme* external force and control exerted over other nations by the US in the past. This is often disguised or presented in a different light. Take 'Colonel' Gadaffi, the Libyan leader. Until just recently, he was the terrorist leader of an evil rogue nation, probably high on the list of "people whose family homes should be bombed in the name of freedom"; however, now that he's co-operating with the US's wishes by opening his country's WMD facilities to inspection, he's the new bestest buddy of the UK-US leaders. A decisions made "of his own free will", but obviously the only choice he could've made to ensure that his country can make socio-economic progress and avoid getting bombed into the last epoch.

I have to agree with The Captain, though. Opinion and perspective have a lot of sway in matters like these, but an absolutist statement like "I'm right and you're not" doesn't really help much. All we can really do is contribute our own viewpoints and interpretations, and more importantly, our reasons for believing what we do.

But, on a strictly literal construction, the United States aren't an empire.