Who exactly rules the United States? According to the nation’s founding documents, the sovereign power over the republic is its people. They elect legislators to represent them in making the nation’s laws. Through an indirect process, they choose an executive to administer the national government, who enforces those laws and also conducts day-to-day foreign policy in both wartime and peacetime.

But whenever the president of the United States wants to make lasting or especially significant changes, the Constitution demands Congress’s involvement. That applies specifically to foreign policy in three ways: First, only Congress can declare or create a state of war. Second, the U.S. Senate must ratify all treaties with foreign powers. Third, Congress can cut off authority and funding for policies it opposes.