and you wanna play with the War Powers Act of 1973?
War Powers Act of 1973 said:
The constitutional powers of the President as Commander-in-Chief to introduce United States Armed Forces into hostilities, or into situations where imminent involvement in hostilities is clearly indicated by the circumstances, are exercised only pursuant to (1) a declaration of war, (2) specific statutory authorization, or (3) a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.
Now, because these terrorists did attack american soil, he had the right to send troops to hunt out these terrorists and anyone that harbored them. Such as Afghanistan and there was belief of terrorist being harbored in Iraq. True or not.. the american people believed it and congress represents the american people and I'm sure they had thoughts of Iraq harboring troops. And though he prolly never got a formal approval in public from Congress there's no proof he never got another kind of approval. And surely he consults with Congress when it comes to sending troops to hostile areas because Congress is the one that pays the military budget, not the President. The President can deploy them but not pay them.