Space-Based Weapons

Weapons deployed from space. Space-based weapons fall into three general categories—those that defend against ballistic missiles, those that attack or defend satellites, and those that attack terrestrial targets. Currently in these categories, land-based systems are the only weapons to have been deployed. To defend against space-based weapons, two types of land-based systems have been tested—antisatellite weapons (ASATs), which have been under development since the 1960s, and ground-based lasers that impair or disable satellites.

Outer space has been used for military purposes—such as reconnaissance missions or targeting—since the launch of the first Sputnik by the Soviet Union in 1957. In 1959, the UN General Assembly set up the Committee on the Peaceful Uses of Outer Space (COPUOS) to promote international cooperation in space. Shortly after the Sputnik launch, the fear of bombardment satellites prompted both the Soviet Union and the United States to research space weapons for defensive and offensive purposes. While the development of submarine-launched ballistic missiles served to limit offensive space weapons, research into defensive space weapons continued.

In the 1960s, antisatellite (ASAT) weapons were developed to disable enemy satellites. These early antisatellite weapons consisted of missiles packing high explosives and shrapnel; kinetic weapons were investigated later. Although many ASAT weapons tested by both the United States and the Soviet Union failed to perform as expected, and treaties were signed to limit the deployment of space weapons, research into new weapons systems continued.

In the late 1990s, the U.S. Army began work on the kinetic energy antisatellite system (KEASAT), which fires a multitude of pellets to slow down enemy satellites, forcing them to burn up in the atmosphere. Ground-based lasers have also been successfully tested. In 1997, the U.S. military tested a chemical laser against a satellite, temporarily disabling its optical sensors. Russia was known to have tested such weapons as well.

The weaponization of space is controlled through a number of norms and treaties, most notably the 1967 Outer Space Treaty, which prohibits the deployment of weapons of mass destruction in space and was signed by 97 countries, including the United States. The treaty bans weapons of mass destruction, defined as “nuclear weapons or any other kinds of weapons of mass destruction,” from space. However, it does not prohibit the launching of ballistic missiles, such as ICBMs, through space. What constitutes a weapon of mass destruction is also under debate, and so many experts feel that the Outer Space Treaty is outdated.

The second most important treaty that pertains to space weapons is the Antiballistic Missile (ABM) Treaty. Signed by the United States and the Soviet Union in 1972, the ABM treaty constrained each country's antimissile defense to two fixed, ground-based defenses of 100 missile interceptors each. The ABM treaty also prohibited interference with monitoring satellites. Concerns that a nationwide defense system would spur a renewed arms race caused the Soviet Union and the United States to reduce the number by half. Both sides reasoned that a nuclear first-strike policy was unacceptable and, ultimately, that remaining vulnerable to each other's offensive nuclear weapons, while maintaining a policy aimed at deterrence, was the lesser of two evils.

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