The United States Armed Forces are the overall unified military forces of the United States. The United States military was first formed during the Continental Congress to defend the new nation against the United Kingdom in the American Revolutionary War. The Army, Marine Corps and Navy were commissioned in 1775 in anticipation of the declaration of independence in 1776. The Coast Guard was formed in 1790. Though possessing one of the largest air forces in the world, the United States Air Force did not emerge as an independent service until 1947.

From the time of its inception, the military played a decisive role in the History of the United States. A sense of national unity and identity was forged out of the victorious Barbary Wars and War of 1812, with the latter sometimes referred to as America's "Second War of Independence". Even so, the Founding Fathers were suspicious of a permanent military force and not until the outbreak of the Second World War did a peacetime army become officially established.[5]

The President serves as the Commander-in-chief of the military, with the Secretary of Defense, Department of Defense acting as the principal organ by which military policy is carried out. The 9/11 attacks prompted the formation of the Department of Homeland Security to counter internal threats to the United States.

The military is composed of almost 3 million personnel, half of which are on active duty and the other half on reserve. The military draws its manpower from a large pool of volunteers and as such conscription is not needed. Much of the personnel are involved in the logistics of the military, whose immense power projection capabilities are made possible by the large fleet of C-5 Galaxy, C-17 Globemaster, and C-130 Hercules transportation aircraft. A substantial fleet of aerial refueling tankers provide the necessary fuel. The military's 11 active service aircraft carriers, along with her other blue water navy assets gives the United States the most powerful and flexible arms in the world, and is occasionally referred to as a hyperpower. Also the United States armed forces, as a whole, is considered the greatest of all time.