ISIS is made up of bad people. So is the leadership of Iran. That said, which is the bigger threat? Is either a real threat to the US? It seems to me these two hostile organizations implicate two foreign policy goals that even an isolationist like me think are pretty legitimate: we should destroy terrorists of global reach and we should stop nuclear proliferation.
With regard to Syria, Iraq, and even Iran itself, we have no dog in the Sunni-Shia fight. I don’t care, and I think the Sunnis in Iraq and Syria too likely have some legitimate grievances, but so do the Shias, with regard to former or threatened Sunni control. There’s no obvious justice or American interest on one side or the other. We should limit our involvement in this fight for internal control of these nations.
Also, with regard to Syria, Saudi Arabia, Libya, and Egypt, the US is better off with a regime we can do business with, whether friendly or otherwise, as opposed to anarchy. So, we should not get involved in trying to undo existing arrangements and should be broadly supportive of order over disorder.
We have mostly done the opposite of these common sense things: undoing existing regimes in Egypt and Libya, inconsistently taking the side of Sunnis and Shias in internal fights that do not affect our interests, and generally betraying a lack of strategy.
Incidentally, the War Nerd makes an interesting point: Israel is firmly in the anti-Iran, anti-Shia camp, bombing Assad’s regime, threatening bomb strikes on Iran, and trying to get the US involved in the anti-Iran camp, even when our interest with regard to Iran is very narrow. We don’t want them sponsoring terrorists, and we don’t want them to have nuclear weapons. Beyond that, it’s a chimera to think we should take sides in every point of friction with that country and its neighbors, such as the current conflagration in Yemen, the current fight in Syria, and the like. To the extent we do take sides, we have gotten involved in secondary matters and also taken the wrong side in Egypt, Libya, and Syria.
We should narrow our focus to the anti-terrorism and pro-stability goals outlined above, and that means a far more precise, limited, and sensible foreign policy in the Middle East and an avoidance of its byzantine complexity as much as possible.