Maliki & Co. are afraid we are arming Sunnis for the civil war to come. On the other hand, we might be creating a rough balance of forces that would act as a deterrent to all-out civil war and encourage a relatively peaceful accommodation.
Blackadder Goes Forth :
Blackadder: You see, Baldrick, in order to prevent a war in Europe, two super blocs developed: us, the French and the Russians on one side, and the Germans and Austro-Hungary on the other. The idea was to have two vast, opposing armies, each acting as the other's deterrent. That way, there could never be a war.
Baldrick: Except, well, this is sort of a war, isn't it?
Blackadder: That's right, there was one tiny flaw in the plan.
George: Oh, what was that?
Blackadder: It was bollocks.