Congress in 1973 passed War Powers Resolution (also known as the War Powers Act).
The main purpose of the resolution was to assure that both the executive and legislative branches participate in decisions that might get the United States involved in war. Congress wanted to circumscribe the president's authority to use armed forces abroad without a declaration of war or other congressional authorization, yet provide enough flexibility to permit the president to respond to attack or other emergencies.
We the people call for the Impeachment of President Barack Obama for blatantly overstepping his authority by not notifying Congress in advance of sending troops to Samalia on Fri 1/11/13 to assist the French in a failed rescue mission. Congress was not notified until 2 days afterward.