So we can just put our troops anywhere and then declare a national security situation?
What troops did Trump put there???
Somewhat over-simplistically, the President is the commander in chief under the Constitution. The President thus has the constitutional authority to command the armed forces how he/she sees fit. The power to declare war, which is something more than just the use of military force, as well as raise funds for armies/navies, was reserved to congress. Everyone agrees the President can send the armed forces wherever, including early in history to the Barbary coast to fight pirates without a declararation of war (the famous shores of Tripoli), but it wasn’t until the Viet Nam “conflict” that Congress decided to formally attempt to restrict what the President could do, and that was what was called the War Powers Act, which requires the President to notify congress of any military actions within a certain time period, and if after 100 days, Congress hasn’t authorized further action, to withdraw the troops. The constitutional question, actually, is whether Congress has the Constitutional authority to restrict the President with the War Powers Act.