The United States Air Force Security Forces (SF) are the ground combat force and military police service of the U.S. Air Force and U.S. Space Force. The USAF Security Forces were formerly known as Military Police (MP), Air Police (AP), and Security Police (SP) at various points in their history.

As outlined in Department of the Air Force publications, Security Forces are responsible for protecting, defending, and fighting to ensure U.S. Air Force, joint, and coalition mission success. They are responsible not only for installation law and discipline enforcement, but also base defense and ground combat.

The USAF uses the term Air Base Ground Defense (ABGD) for defense of U.S. Air Force bases. This specialty is filled by members of the Air Force Security Forces, who serve not only as military law enforcement officers, but also as ground combat troops defending U.S. air bases around the world from possible attacks. In these capacities, their duties are similar to a combination of the roles performed in the UK military by the RAF Regiment and RAF Police.

Camp Bullis in Texas is where all levels of Air Base Ground Defense (ABGD) are instructed, the course ranges in length from 4–6 weeks. In these weeks of training Air Force Security Forces are taught to operate the following weapons: M4 Carbine, M-18, M-9, M-203, M-240B, M-249 (SAW), MK-19, as well as other base defense weapons and tools. In 1966-1969, sentry dog teams used the Smith & Wesson K-38 Combat Masterpiece.

Under the Interservice Agreement between the United States Air Force and the United States Army, the U.S. Air Force is responsible for ground combat operations to defend U.S. air bases. Air Force Security Forces fulfill this mission, and, as such, are trained in the whole range of infantry tactics, to include patrolling, close quarters battle, defense in depth, crew-served weapons, and other ground combat tactics.

The director of Security Forces is a Brigadier General and the highest-ranking Security Forces officer, sometimes referred to as the "Top Cop". The director of Security Forces reports to the deputy chief of staff of the Air Force for logistics, engineering and force protection. The director of Security Forces has the responsibility to develop policy, doctrine, and guidance for Security Forces and serves as the executive agent for the Department of Defense Military Working Dog Program.

The deputy director of Security Forces acts as the second-in-command to the director of Security Forces. The Security Forces Career Field Manager is a chief master sergeant and the senior enlisted Defender, acting as an adviser to the director of Air Force Security Forces.

The USAF Security Forces lineage can be traced to its beginning in WWII with the German blitzkrieg. Blitzkrieg relied on swift attacks by land and air. One of the tactics employed by blitzkrieg was the use of paratroops and airborne forces to capture, or destroy in advance, air bases. A key turning point in air base defensive thinking came with the loss of the Battle of Crete to German forces and capture of the British air base at Maleme in 1941. This single action led then Prime Minister Winston Churchill to study British air base defense policy, and in a condemning memo to the Secretary of State for Air and to the Chief of the Air Staff dated 29 June 1941, Churchill stated he would no longer tolerate the shortcomings of the Royal Air Force (RAF), in which half a million RAF personnel had no combat role. He ordered that all airmen be armed and ready "to fight and die in defense of their air fields" and that every airfield should be a stronghold of fighting air-ground men and not "uniformed civilians in the prime of life protected by detachments of soldiers." Churchill's directive resulted in formation of the RAF Regiment.