I don't think it'll be a frontal war, either. It's going to be little subtleties that will kill us if we widthdraw from the UN. Countries will stop trading with us. Our economy will falter. Countries will be on alert, and the first thing we do that pisses them off can beget guerilla tactics by certain countries. We will basically be destroyed from the inside. As of today, there is no millitary power in the world that can come close with America, but we can't completely cut ourselves off from the world. We're not that capable of being independent, and I gurantee you, leaving the UN will send the rest of the world the message that "We thing we're badasses and better than everyone else." While you may believe that to be true, every country has it's sense of pride, and no country is ever going to accept that.