The arts of war say taking enemy territory is hard, because it is their turf. U should never try it, unless u have a significantly superior army. Even then, it might not be enough and if that is the case, u will run out of army and the enemy can take ur land. This have been evidence again and again, E.g. American Revolution War. It said it is, unless u have no choice, it is better to have ur enemy surrounded with you superior army, if ur army is strong enough and starve them out of the war. This seem to be Obama's strategy with ISIS, but how long would it take, to starve ISIS into defeat?