Russian Space Forces in the context of "Russian Aerospace Defence Forces"

The United States Space Force (USSF) is the space service branch of the United States Armed Forces, and was established on 20 December 2019. Part of the United States Department of Defense, it is one of the six armed forces of the United States and one of the eight uniformed services of the United States. It is the second independent space force to have been formed, after the Russian Space Forces; together with that of China, it is one of only two still extant.

The United States Space Force traces its origins to the Air Force, Army, and Navy's military space programs created during the beginning of the Cold War. US military space forces first participated in combat operations during the Vietnam War and have participated in every U.S. military operation since, most notably in the Gulf War, which has been referred to as the "first space war". The Strategic Defense Initiative and creation of Air Force Space Command in the 1980s marked a renaissance for military space operations.

A space force is a military branch of a nation's armed forces that conducts military operations in outer space and space warfare. The world's first space force was the Russian Space Forces, established in 1992 as an independent military service. However, it lost its independence twice, first being absorbed into the Strategic Rocket Forces from 1997–2001 and 2001–2011, then it merged with the Russian Air Force to form the Russian Aerospace Forces in 2015, where it now exists as a sub-branch. As of 2025, there are two independent space forces: the United States Space Force and China's People's Liberation Army Aerospace Force.

Countries with smaller or developing space forces may combine their air and space forces under a single military branch, such as the Russian Aerospace Forces, Spanish Air and Space Force, French Air and Space Force, or Iranian Islamic Revolutionary Guard Corps Aerospace Force, or put them in an independent defense agency, such as the Indian Defence Space Agency. Countries with nascent military space capabilities usually organize them within their air forces.

Space warfare is combat in which one or more belligerents are in outer space. The scope of space warfare includes ground-to-space warfare, such as attacking satellites from the Earth; space-to-space warfare, such as satellites attacking satellites; and space-to-ground warfare, such as satellites attacking Earth-based targets. The 1967 Outer Space Treaty forms the basis of space law; it prohibits permanent basing of weapons of mass destruction including nuclear weapons in space and the military use of celestial bodies, but does not prohibit the military use of Earth orbit or military space forces. Independent space forces are operated by the United States (US Space Force) and China (People's Liberation Army Aerospace Force). Russia operates significant space assets under the Russian Space Forces.

The Cold War prompted the start of the militarization of space. Military satellites have been launched since the late 1950s, for communications, navigation, reconnaissance and munitions guidance. The Gulf War is sometimes called the "first space war" for the US' use of these capabilities. The use of Starlink satellites by Ukraine has played a major role in the Russian-Ukrainian War.