Our treaty obligations under NATO (let alone the UN Charter) do not remove the power of Congress under the Constitution to declare war.
Congress need not defund the entire DOD either, they can decide that no U.S. money will go to funding any military missions in Libya or to NATO or to the UN or to any other cause that they feel doesn't deserve taxpayer money.
Not a very high quality counterargument.
Our treaty obligations under NATO (let alone the UN Charter) do not remove the power of Congress under the Constitution to declare war.
So the treaties authorize executive actions only when Congress is in the mood? They should have written that into the text of treaties. And the definition of war is not "any time the US military does anything" - to have a war you need to have a legitimate sovereign government to declare war against. Otherwise the term is meaningless.
Congress need not defund the entire DOD either, they can decide that no U.S. money will go to funding any military missions in Libya or to NATO or to the UN or to any other cause that they feel doesn't deserve taxpayer money.
The Constitution says nothing of the kind. They can raise or support armies or they can decline to. They don't get to tell the Commander in Chief how or how much he is allowed to command.
If they want to rewrite the DOD budget next time around, fine. But ex post facto law is unconstitutional.