I must answer this even though very late, we could of course do the whole damn thing ourselves (we are almost always at least 90% of the force) but he is trying to get other countries to commit troops meaning they are for our cause. It is a sneaky political thing to do, but thats how the world knows if your in or your out. Kind of like if you kill someone to get in a gang, theres no turning back. If you're sending peoples kids to die for a cause then you cant back out and say you didnt support it later.
At least thats how I view the whole situation though maybe I'm full of shit but thats what I think is happening.