To prevent ISIS or Iran from becoming much bigger threats. Again, the main principle is to prevent a Muhammad wannabe from unifying the Muslim world that incidentally includes the vast majority of the world's oil resources.
But we are taking sides. We sided with the Shia in Iraq, then we armed and trained the rebels (Sunni ISIS in Syria and Libya) and now we hear that we might team up with Shia Iran to fight ISIS (which, did I mention we armed and trained).
I’m not seeing a clear objective (much less strategy) here.
Also, why are these “the world’s oil resources”. Does the rest of the world have a right oil and other resources on American soil? I’m not getting that angle either.