This is a big mess with international repercussions that has to be dealt with in some way. But this is why for centuries countries have been sending only this or that, advisors and/or expeditionary forces all a prelude to full scale military intervention. If nothing else learn from recent history if you don't want to go back. The question What will happen when the US leaves in full? MUST be answered first. Either we stay out and wait to until it directly affects us or we sell the prospect of long term occupation with more years of abushes, ieds and suicide bombers/attackers.