So the US decided they wanted Panama to build a canal, fomented revolution in Panama, and somehow claimed rights to have a warship in the area, preventing the rebellion from being quelled, based on a treaty with a country that no longer existed that stated that the US couldn't intervene.

Hmm. In some further research, I found this page which goes into a little more detail about the nature of the revolt.

"While careful not to endorse the revolt, Roosevelt discreetly let it be known that the U.S. would view this as a positive development and could be counted on to act accordingly. Critics later charged that Roosevelt conspired to instigate the revolution in Panama. In fact, fearing that the U.S. might choose an alternate route through Nicaragua, an enterprising group of Panamanian businessmen--anxious to reap the commercial benefits of the canal--seized the moment. There had been numerous uprisings in the region, and the U.S. had helped suppress them in the past. As Roosevelt later put it, "While I was President I kept my foot on these revolutions… [in this case] I did not have to foment it; I simply lifted my foot."

So it doesn't seem to me that the U.S. encouraged the revolt, it just sounds like the revolt was there and they chose to selectively not stop it because it was in their interest. Sending the warships in is a different story, and obviously they were protecting their interests in the canal.

So maybe 100 years ago, through careful maneuvering, a bit of military might, and a lot of cash, we got control of a canal in Panama. Which we've since relinquished control of entirely. That makes us imperialists today?