The powers of the president of the United States include those explicitly granted by Article II of the United States Constitution as well as those granted by Acts of Congress, implied powers, and also a great deal of soft power that is attached to the presidency.
The Constitution explicitly assigns the president the power to sign or veto legislation, command the armed forces, ask for the written opinion of their Cabinet, convene or adjourn Congress, grant reprieves and pardons, and receive ambassadors. The president shall take care that the laws are faithfully executed and the president has the power to appoint and remove executive officers. The president may make treaties, which need to be ratified by two-thirds of the Senate, and is accorded those foreign-affairs functions not otherwise granted to Congress or shared with the Senate. Thus, the president can control the formation and communication of foreign policy and can direct the nation's diplomatic corps. The president may also appoint Article III judges and some officers with the advice and consent of the U.S. Senate. In the condition of a Senate recess, the president may make a temporary appointment.
Commander-in-chief
The president is the commander-in-chief of the United States Armed Forces as well as all federalized United States Militia and may exercise supreme operational command and control over them. The president has, in this capacity, plenary power to launch, direct and supervise military operations, order or authorize the deployment of troops, unilaterally launch nuclear weapons, and form military policy with the Department of Defense and Homeland Security. However, the constitutional ability to declare war is vested only in Congress.
Article II of the U.S. Constitution expressly designates the president as:
U.S. ranks have their roots in British military traditions, with the president possessing ultimate authority, but no rank, maintaining a civilian status. Before 1947, the president was the only common superior of the Army (under the secretary of war) and the Navy and Marine Corps (under the secretary of the navy). The National Security Act of 1947, and the 1949 amendments to the same act, created the Department of Defense and the services (Army, Navy, Marine Corps and Air Force) became subject to the "authority, direction and control" of the secretary of defense. The president and the secretary of defense collectively, form the National Command Authority. The present-day operational command of the Armed Forces is delegated from the president to the Department of Defense and is normally exercised through its secretary. The chairman of the Joint Chiefs of Staff and the combatant commands assist with operations as outlined in the presidentially-approved Unified Command Plan (UCP).
The exact degree of authority that the Constitution grants to the president as commander-in-chief has been the subject of much debate throughout American history, with Congress at various times granting the president wide authority and at others attempting to restrict that authority. There is consensus that the framers of the Constitution intended Congress to declare war and the president to direct the war; Alexander Hamilton said that the president, although lacking the power to declare war, would have "the direction of war when authorized or begun", further explaining in Federalist No. 69 that "The President is to be commander-in-chief of the army and navy of the United States. ... It would amount to nothing more than the supreme command and direction of the military and naval forces ... while that of the British king extends to the DECLARING of war and to the RAISING and REGULATING of fleets and armies, all [of] which ... would appertain to the legislature".
Pursuant to the War Powers Resolution of 1973, Congress must authorize any troop deployments longer than 60 days, although that process relies on triggering mechanisms that have never been employed, rendering it ineffectual. Additionally, Congress provides a check to presidential military power through its control over military spending and regulation. Presidents have historically initiated the process for going to war, but critics have charged that there have been several conflicts in which presidents did not get official declarations, including Theodore Roosevelt's military move into Panama in 1903, the Korean War, the Vietnam War, and the invasions of Grenada in 1983 and Panama in 1989.