I don't find this story particularly credible, for a whole raft of reasons. Official accounts certainly deserve skepticism, but the multiplicity of unofficial accounts deserve at least equal skepticism.

I also don't find the legal arguments to be terribly persuasive. Maybe I'm just an American neanderthal, but we all know the UNSC is inutile and "international law" is unenforceable and thus too abstract to be of any real utility. I'd have no issues at all with action without UN authorization IF there was a truly compelling US interest at stake, if the goal was clear, practical, and achievable, if there was a clear plan in place for controlling escalation when the other side calls the bluff, and if the risk/reward and cost/benefit equations justified action.

My problem with the whole proposal is that I don't see any of these criteria being met.