If we go to war we cannot have another war where the military goes to war, the nation has to go to war.
The generation running America today is too self centered to wage war as it was waged in WW2. It will not be George Patton and Curtis LeMay running the war, so we want to be very careful about going in. We need to be Machiavellian, it would not be in our interest to wage a war, but it would serve our interest rather nicely were Iran to be involved in a war. Saddam Hussein was not a choir boy when Reagan was president, but Reagan was able to see past all of that and see a useful SOB. The enemy of my enemy is not my friend, the enemy of my enemy is probably an A-hole too.
Yemen for one is a place that has potential to serve as Iran's Vietnam. It has a roughly 50/50 split between Shia and Sunni, a number of clan factions. I could see that ending up as a proxy war between Saudi Arabia and Iran that would soak up the resources of both nations. Do gooder Pollyannas cause half our problems, I'd take an America First Machiavelli over the bleeding hearts. We should leverage rather than be leveraged.