The 1967 Outer Space Treaty banned weapons of mass destruction in orbit, but it also established that space would be free for all states to use in accordance with international law (including the UN Charter). The Cold War superpowers interpreted the treaty as legitimating and protecting the use of satellites for early warning, crisis communication, verification, and other activities contributing to deterrence stability—but not for aggression.
In recent decades, however, as space-based reconnaissance, communication, and targeting capabilities have become integral elements of modern military operations, strategists and policy makers have explored whether carrying out antisatellite attacks could confer major military advantages without increasing the risk of nuclear war. In theory, the answer might be yes. In practice, it is almost certainly no.
View the entire essay and the other contribution's to the Bulletin's "Space Weapons and the Risk of Nuclear Exchanges" roundtable discussion.