The President has the power to negotiate and make treaties with other countries, but treaties must be approved by a two-thirds vote in the Senate. Most routine international agreements are made through executive agreements between the President and foreign leaders without Senate approval. The President also has the power to recognize the legal existence of other countries. As Commander-in-Chief, the President has authority over military affairs, though Congress can declare war. Presidents have used military action without declarations of war and have expanded wartime powers to nonmilitary areas. Congress passed the War Powers Resolution in 1973 to limit the President's authority during military commitments abroad.