During the Cold War, satellite capabilities reinforced nuclear deterrence because the superpowers relied on them to reinforce second-strike stability for nuclear weapons. Antisatellite technology was deployed, but it was also immature. Today, the broader use of space for conventional power projection, together with more mature target discrimination and antisatellite technology, create strong incentives for both the United States and its adversaries to conduct counter-space operations. The United States’ military power projection is utterly dependent on space assets for command, control, communications, intelligence, and targeting, but satellites are increasingly vulnerable to antisatellite capabilities, including not only direct attacks on satellites but also indirect cyber and electronic warfare interference on satellites, links, and ground-based control infrastructure. Several cross-domain options are available for deterrence both by denial (the threat of effective defense) and by punishment (the threat of retaliation). Unfortunately, the lack of shared norms regarding space warfare has uncertain consequences for escalation dynamics.