Powers of the president of the United States in the context of "United States presidential transition"

The United States Department of Defense (DoD), also referred to as the Department of War (DoW), is an executive department of the U.S. federal government charged with coordinating and supervising the U.S. Armed Forces—the Army, Navy, Marines, Air Force, Space Force, and, for some purposes, the Coast Guard—and related functions and agencies. Headquartered at the Pentagon in Arlington County, Virginia, just outside Washington, D.C., the stated mission of the Department of Defense is "to provide the military forces needed to deter war and ensure our nation's security".

The Department of Defense is headed by the secretary of defense, a cabinet-level head who reports directly to the president of the United States. The president is commander-in-chief of the U.S. armed forces. Beneath the Department of Defense are three subordinate military departments: the Department of the Army, the Department of the Navy, and the Department of the Air Force. In addition, four national intelligence services are subordinate to the Department of Defense: the Defense Intelligence Agency, National Security Agency (NSA), National Geospatial-Intelligence Agency, and National Reconnaissance Office.

The president of the United States (POTUS) is the head of state and head of government of the United States. The president directs the executive branch of the federal government and is the commander-in-chief of the United States Armed Forces.

The power of the presidency has grown since the first president, George Washington, took office in 1789. While presidential power has ebbed and flowed over time, the presidency has played an increasing role in American political life since the beginning of the 20th century, carrying over into the 21st century with some expansions during the presidencies of Franklin D. Roosevelt and George W. Bush. In the 21st century, the president is one of the world's most powerful political figures and the leader of the world's only remaining superpower. As the leader of the nation with the largest economy by nominal GDP, the president possesses significant domestic and international hard and soft power. For much of the 20th century, especially during the Cold War, the U.S. president was often called "the leader of the free world".

The director of national intelligence (DNI) is a cabinet-level United States government intelligence and security official. The position is required by the Intelligence Reform and Terrorism Prevention Act of 2004 to serve as executive head of the United States Intelligence Community (IC) and to direct and oversee the National Intelligence Program (NIP). All 18 IC agencies, including the Central Intelligence Agency (CIA), the Defense Intelligence Agency (DIA) and the National Security Agency (NSA), report directly to the DNI. Other federal agencies with intelligence capabilities also report to the DNI, including the Federal Bureau of Investigation (FBI).

The DNI also serves as the principal advisor to the president of the United States, the National Security Council, and the Homeland Security Council on all intelligence matters. The DNI, supported by the Office of the Director of National Intelligence (ODNI), produces the President's Daily Brief, a highly classified document including intelligence from all IC agencies, shared each morning with the president of the United States. The DNI, who is appointed by the president of the United States and is subject to confirmation by the United States Senate, serves at the pleasure of the president.

The United States secretary of defense (SecDef), secondarily titled the secretary of war (SecWar), is the head of the United States Department of Defense (DoD), the executive department of the U.S. Armed Forces, and is a high-ranking member of the cabinet of the United States. The secretary of defense's position of command and authority over the military is second only to that of the president of the United States, who is the commander-in-chief. This position corresponds to what is generally known as a defense minister in many other countries. The president appoints the secretary of defense with the advice and consent of the Senate, and is by custom a member of the Cabinet and by law a member of the National Security Council.

Subject only to the orders of the president, the secretary of defense is in the chain of command and exercises command and control, for both operational and administrative purposes, over all DoD-administered service branches  – the Army, Marine Corps, Navy, Air Force, and Space Force – as well as the Coast Guard when its command and control is transferred to the Department of Defense. Only the secretary of defense (or the president or Congress) can authorize the transfer of operational control of forces between the three military departments (Department of the Army, the Navy, and the Air Force) and the eleven Unified Combatant Commands.

Article Two of the United States Constitution establishes the executive branch of the federal government, which carries out and enforces federal laws. Article Two vests the power of the executive branch in the office of the president of the United States, lays out the procedures for electing and removing the president, and establishes the president's powers and responsibilities.

Section 1 of Article Two establishes the positions of the president and the vice president, and sets the term of both offices at four years. Section 1's Vesting Clause declares that the executive power of the federal government is vested in the president and, along with the Vesting Clauses of Article One and Article Three, establishes the separation of powers among the three branches of government. Section 1 also establishes the Electoral College, the body charged with electing the president and the vice president. Section 1 provides that each state chooses members of the Electoral College in a manner directed by each state's respective legislature, with the states granted electors equal to their combined representation in both houses of Congress. Section 1 lays out the procedures of the Electoral College and requires the House of Representatives to hold a contingent election to select the president if no individual wins a majority of the electoral vote. Section 1 also sets forth the eligibility requirements for the office of the president, provides procedures in case of a presidential vacancy, and requires the president to take an oath of office.

The oath of office of the president of the United States is the oath or affirmation that the president of the United States takes upon assuming office. The wording of the oath is specified in Article II, Section One, Clause 8, of the United States Constitution, and a new president is required to take it before exercising or carrying out any official powers or duties.

This clause is one of three oath or affirmation clauses in the Constitution, but it is the only one that actually specifies the words that must be spoken. Article I, Section 3 requires Senators, when sitting to try impeachments, to be "on Oath or Affirmation." Article VI, Clause 3, similarly requires the persons specified therein to "be bound by oath or affirmation, to support this Constitution." The presidential oath requires much more than that general oath of allegiance and fidelity. This clause enjoins the new president to swear or affirm: "I will to the best of my ability, preserve, protect and defend the Constitution of the United States."