A new and provocative take on the formerly classified history of accelerating superpower military competition in space in the late Cold War and beyond. In March 1983, President Ronald Reagan shocked the world when he established the Strategic Defense Initiative (SDI), derisively known as “Star Wars,” a space-based missile defense program that aimed to protect the US from nuclear attack. In Weapons in Space, Aaron Bateman draws from recently declassified American, European, and Soviet documents to give an insightful account of SDI, situating it within a new phase in the militarization of space after the superpower détente fell apart in the 1970s. In doing so, Bateman reveals the largely secret role of military space technologies in late–Cold War US defense strategy and foreign relations. In contrast to existing narratives, Weapons in Space shows how tension over the role of military space technologies in American statecraft was a central source of SDI’s controversy, even more so than questions of technical feasibility. By detailing the participation of Western European countries in SDI research and development, Bateman reframes space militarization in the 1970s and 1980s as an international phenomenon. He further reveals that even though SDI did not come to fruition, it obstructed diplomatic efforts to create new arms control limits in space. Consequently, Weapons in Space carries the legacy of SDI into the post–Cold War era and shows how this controversial program continues to shape the global discourse about instability in space—and the growing anxieties about a twenty-first-century space arms race.