The Space Force is the smallest U.S. armed service, consisting of 4,840 personnel and operating 77 spacecraft. Major spacecraft and systems include the Global Positioning System constellation, military satellite communications constellations, Boeing X-37B spaceplane, U.S. missile warning system, U.S. space surveillance network, and the Satellite Control Network. Under the Goldwater–Nichols Act, the Space Force is responsible for organizing, training, and equipping space forces, which are then presented to the unified combatant commands, predominantly to United States Space Command, for operational employment.
The U.S. Space Force traces its roots to the beginning of the Cold War, with the first Army Air Forces space programs starting in 1945. In 1954, the Western Development Division, under General Bernard Schriever, was established as the first dedicated space organization within the U.S. Armed Forces and continues to exist as the Space Force's Space and Missile Systems Center. Military space forces were organized under several different Air Force major commands until they were unified when Air Force Space Command was established on 1 September 1982. U.S. space forces first began conducting combat support operations in the Vietnam War and continued to provide satellite communications, weather, and navigation support during the 1982 Falklands War, 1983 United States invasion of Grenada, 1986 United States bombing of Libya, and 1989 United States invasion of Panama. The first major employment of space forces culminated in the Gulf War, where they proved so critical to the U.S.-led coalition, that it is sometimes referred to as the first space war.
The first discussions of creating a military space service occurred in 1958, with the idea being considered by President Ronald Reagan as well in 1982. The 2001 Space Commission argued for the creation of a Space Corps between 2007 and 2011, and a bipartisan proposal in the U.S. Congress would have created a U.S. Space Corps in 2017. On 20 December 2019, the United States Space Force Act, developed by Democratic Representative Jim Cooper and Republican Representative Mike Rogers, was signed as part of the National Defense Authorization Act by President Donald Trump, reorganizing Air Force Space Command into the United States Space Force, and creating the first new independent military service since the Army Air Forces were reorganized as the U.S. Air Force in 1947.