Our survival depends on winning the war against Islamofascist terrorism. Which has what to do with deploying US ground troops in an Iraqi civil war zone with no identifiable enemy and no identifiable mission other than handy target?
Or perhaps you are suggesting that, in order for the US to survive, we need to have ground troops patrolling in Pakistan, Syria, Palestine, Lebanon, Iran, Saudi Arabia, etc., all of which are active participants in the spread of Islamic terrorism.
"Which has what to do with deploying US ground troops in an Iraqi civil war zone with no identifiable enemy and no identifiable mission other than handy target?"
Troops are in Iraq now, because according to the Geneva conventions, if you Country A, take over country B, you are responsible for country B to help develop a stable nation. I guess that area taken over could be added to country A's national boundaries.
So your question of why we are their is under the Geneva conventions the USA has a responsibility to help develop a stable government.
Just be thankful that the Military has had a mostly free hand. Under the Rats, you could see a political zone north of the 38th parallel (reference to Vietnam) that would be a safe zone for all the terrorist.