Anxiety over the escalatory potential of tactical nuclear weapons peaked in the 1970s when the Soviet Union began deploying the SS-20 intermediate-range ballistic missile (capable of striking cities in Europe, but not the U.S.) and Washington responded with plans to deploy nuclear-armed, ground-launched cruise missiles and the Pershing-II ballistic missile in Europe. The announcement of such plans provoked massive antinuclear demonstrations across Europe and the United States. On December 8, 1987, at a time when worries had been growing about how a nuclear conflagration in Europe might trigger an all-out nuclear exchange between the superpowers, President Ronald Reagan and Soviet leader Mikhail Gorbachev signed the Intermediate-Range Nuclear Forces (INF) Treaty.