So did the two Chinese factions more than half a century ago. Ideology can lead to war, even the two parties are within the same sovereign country. It's not happening today in U.S. is because they've realized that war is expensive and unefficient. Confining the "war" inside the capitol building is so much cheaper.

If there is a "world congress" which, unlike the non-functioning U.N., has the real power over its fellow countries, U.S. would probably do the same thing and try to manipulate other countries inside that congress.