During the last couple of years of the Reagan administration, we were supplying arms to both Iraq and Iran who were at war with each other. The American public was tending to side with Iraq, as we were still pissed about Iran holding US citizens as hostages. Then just a few years later we end up invading Iraq. Then we invaded Iraq a second time.
Now we have Iran supporting and supplying the Iraq government with arms and we are tending to side with the Kurds, but only because they are fighting ISIS, and we view the Kurds the lessor of evils. I'm not sure that ANY of these people are exactly the good guys. That's the reason why I see no reason for the US to rush in to save anyone or to chose sided. this really isn't our war, it's probably not in our best interest to get involved any further than keeping ISIS contained.
As long as ISIS is contained, it's of little consequence to the US if these people kill each other off. I've got a friend who keeps insisting that we should just "nuke 'em all", but I wonder why he thinks we should waste a nuke in that part of the world, seems to me that they are doing a mighty find job of killing each other without our help.