Please tell us the last time the UN put together an effective multinational military operation by which to fight an Islamic entity of any kind.
That's the first question. Here's the corollary:
Given that the UN fancies itself a legitimate global government... Given that it is outrageously corrupt, hideously expensive, impossibly beaureaucratic, invariably inept, and structurally unaccountable...
Do we really want the UN to have a capable military?
Granted an effective UN anything would be a first. And no, I don't want to see the UN have an effective military capability. But I don't want the UN shaping world and domestic opinion against the war either. So lets put the UN on the front line and when they prove ineffective, then we tell them to leave in disgrace for failing to handle the situation.
Yes, given that the UN is "impossibly bureaucratic" and "inept", we shouldn't have to worry about the UN having a capable military.