After the September 11 attacks, the United States became involved in military conflicts in both Iraq and Afghanistan. Even though the attacks were clear acts of war, the President couldn't just declare war and go after those responsible. It was important that America act quickly, but there was a process that had to be followed to make sure going to war was something that was in our national interests.

It wasn't always this way. In this lesson you will learn about how the war powers of Congress and the President changed as a result of the Vietnam War.

The Constitution mentions war powers in two sections. In Article I, Section 8, it grants Congress the powers to declare war, raise and support armies, and to provide and maintain a navy. In Article II, Section 2, it declares that the President is "Commander in Chief of the Army and Navy of the United States."

The Constitution divides war powers between the legislative branch and the executive branch. The writers of the Constitution did not want one branch to have all the power during wartime. Both branches need each other when making decisions about war.