What do you call it when an OT thread goes OT?
Just to be clear, only congress can DECLARE war, meaning committing the full resources of the US to a war.
The president can COMMAND troops to engage in battle at any time, usually in the name of self-defense.
The War Powers act imposed the deadline for the President to gain congressional approval for the use of military force or withdraw and stand-down said force.
However, in theory Congress can at any time convene hearings, compell witnesses to testify, pass binding resolutions, and revoke the expenditures necessary to sustain military operations.
In these circumstances I do not expect Congress to assert their authority until it becomes clear on which side of the issue they can safely take. Congress was completely AWOL when the action in Afghanistan was started. Only when it became clear that it would not be a complete quagmire did they get around to authorizing the use of force.