The US dropped out because Trump is smart enough to know that American interests would not be served getting embroiled in another Middle Eastern war.
Not a full scale war. A full scale war only be practical when US is sole superpower and spare resources.
I mean a limited air strike war, destroy enemies/rival strength, stress their defense/social/economical burden. US still can do it even within next 10 years.
I am not a supporter of doing this, I hate war and killing. Don't make me wrong.
I am just analyzing what options US has and how to leverage the resource for hegemony. ME is a bleeding wound for US, the longer US linger, the worse. US is oil self-sufficient, while US opponent is not.
From pure US hegemony perspective, eliminate regional rivals, and shift power to long term opponent is a wise decision.
The problem of Iraq war is not the strategy, it's the leadership and execution. US should not involved in Iraq too much in the first place, economic and military pressure is good enough to keep Saddam in bay.
But since US already involved, the question should be how to use their power more wisely. Instead of trying to control the land and oil, build government and US style democracy, US should withdraw the military boots quickly and monitor the situation.
See how Deng Xiaoping hit Vietnam? Hit and withdraw, keep military/social/economical pressure, that's it.
