The Space Force’s capstone document, Spacepower, defines space as the domain of orbital flight, including vehicles that leave and then reenter the atmosphere without making a single orbit, such as ballistic missiles.2 While some definitions of space rely on a judgment of where the Earth’s atmosphere ends (many multilateral agreements use the Kármán line, which is 100 km above sea level), the Space Force doctrine resists using any specific physical demarcation.3
Regarding the militarization of space, Spacepower defines it as the use of space for military purposes, whether those purposes include transit of objects (missiles) or the use of satellites for surveillance or communications. The militarization of space began in the final years of World War II, when Germany began to strike England with V-2 ballistic missiles.4 After the war, both the United States and the Soviet Union used technology and scientists from Germany to establish and develop their own space programs, eventually resulting in a “space race” to achieve various milestones of national prestige.5
The complexity and importance of military operations in space have changed considerably since the 1950s, often in unpredictable ways. While the military value of ballistic missiles was immediately apparent, the implications of space‐based satellites for military reconnaissance and communication dawned slowly. The first spy satellites entered service in 1960. Though they took lower‐quality photographs compared to existing reconnaissance aircraft, they also could not be intercepted. Prior to the establishment of sufficiently high‐bandwidth communications, satellites would drop physical film for ships and aircraft to recover. The United States launched the first dedicated military communications satellite in 1966, significantly easing problems of military signal transfer.6
Space quickly became central to maintaining Cold War nuclear deterrence, as both the Soviet Union and United States used satellites to detect any launch or other first‐strike activity by the other side.7 This linked space directly to nuclear warfighting, with the consequence that antisatellite activity carried a high risk of nuclear response. Both the United States and Soviet Union had experimented with antisatellite weapons in the late 1950s and early 1960s without appreciable success but with considerable lessons learned.8
In the 1970s and 1980s the number and sophistication of satellites expanded rapidly. The U.S. military achieved new operational capabilities in space, delivering intelligence, communications, and navigational systems to soldiers. As demonstrated in the Gulf War, the U.S. military could use space to fight more effectively in conventional conflicts, essentially making the battlefield transparent.9 In short order, nearly the entirety of modern U.S. military operations, by all services and at all levels of intensity, required the use of space. Satellites identify targets, track their movement, transfer data to shooters, and monitor the results of the attack. Satellites enable commanders to have a full understanding of the battlefield, allowing them to communicate with their forces and offering information about the size and movements of enemy forces.
Civilian use of space also increased alongside changes in the military use of space. Communications satellites now dominate the international telecommunications industry, providing connectivity to firms and individuals around the world. Businesses, universities, and governments have built this ready connectivity into the basic structure of their daily operations. This has enabled what Richard Baldwin refers to as the second “Great Acceleration” of globalization.10 If space went away, so to speak, many people would struggle to find their way to the local grocery store due to a lack of the Global Positioning System. The way knowledge moves between nations, firms, and individuals depends on easy access to space. Preventing such access could cause massive social and economic disruption.
But the military and civilian advantages created by greater use of space have also created new vulnerabilities. The U.S. military has become dependent on space to conduct its basic operations, just as the U.S. civilian economy’s dependence on space has increased. Competitors have access to space and increasingly the technologies necessary to attack U.S. satellites. Consequently, competitors can threaten damage against both the U.S. military and civilian economy by attacking space infrastructure. Moreover, the United States can no longer assume that satellites’ role in the nuclear enterprise will deter foes from attacking satellites tasked with conventional military missions.11
In 2007, China destroyed one of its satellites in low‐Earth orbit (LEO), demonstrating its ability to threaten core U.S. communications infrastructure. Unfortunately, the satellite’s destruction produced an extensive debris field, some of which remains in orbit today. This field, full of fast‐moving orbital objects, poses a long‐term threat to the military and civilian use of LEO. As the demonstration made clear, a war in space could result in the long‐term loss of some of the most valuable real estate in LEO, which would not only disrupt military operations but could also render civilian space infrastructure inoperable.12 The United States responded to China’s test with its own antisatellite test, during which it launched a Standard Missile‐3 missile defense interceptor from an Aegis weapons system on a U.S. Navy warship.13 The U.S. test destroyed a satellite but produced a smaller debris field because it occurred at a lower altitude than the Chinese test, with most debris burning up as it reentered Earth’s atmosphere. Russia and India have both conducted antisatellite tests subsequently, with the Indian test leaving a debris field similar to that of the 2008 American test.14
Several major powers now have the demonstrated capacity to undertake antisatellite attacks that could destroy their opponents’ civilian and military communications infrastructures. Most of these antisatellite weapons involve interceptors launched from ground, sea, and air platforms. Moreover, the use of space assets to damage or destroy satellites also appears technically feasible. The argument that space is more important now than ever before is strategically sound. The U.S. civilian economy depends on space for its connectivity, and thus its prosperity. The U.S. military depends on space for communications and reconnaissance. However, concluding that space represents a key strategic interest for the United States does not imply or necessitate any specific institutional framework for pursuing that interest.