Germans committing genocide was not why the US entered the war, though.

This is a disgusting comment. There exists no parallel here. The nazis engaged in a systematic, colossal campaign to exterminate as many Jewish people as possible. You are saying that this is somehow equivalent to Israel simply existing. Iran became hostile to Israel and to the US in 1979 with the Islamic Revolution.

Also, the US entered WWII because of Pearl Harbor, and engaged in a normal war against the Axis. Iran engages in terrorism by financing and arming terrorist groups that perform terrorist attacks on civilians. The US action in WWII defeated the nazis. The actions of the Iranian dictatorship caused deaths and terrors targeted at civilians in other countries and destroyed the lives of its own people in Iran.

The US entered WW2 because Pearl Harbor was attacked, not Germans committing genocide.