Why Not Leave Libya Alone?

In for a penny, in for a pound. Another political post.

Muammar Gaddafi has been handed a "non-negotiable ultimatum" by Barack Obama to accept an immediate ceasefire, pull back from Libyan rebel strongholds and permit humanitarian assistance – or face the full onslaught of UN-endorsed air strikes. (Guardian)

Last I heard, it was the US Congress, not the UN, that had the power to declare war on a foreign nation.

UN-endorsed air strikes? What does that even mean? Does the UN have its own planes? Using military aggression on a foreign country is an act of war, regardless of whether it is done by planes, trains or automobiles. For the US to be involved, Congress has to grant approval. Full stop.

Do I think Gadaffi is an asshole tyrant? Yes, of course. But if we are going to be bravely intervening to help rebels maybe we could've started off with Tienanmen Square or even better, the 1956 Hungarian uprising. Where are the UN resolutions against Myanmar and the Congo?

Addendum:

The President does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation. -Senator Barack Obama, 2007 (source)