Presidency of Ronald Reagan to forestall the possibility of an agreement between the United States and the Soviet Union. Nonetheless, both Gorbachev and Reagan agreed to continue arms control negotiations at the October 1986 Reykjavík Summit. At the summit, Gorbachev and Reagan closed in on an agreement to greatly reduce or eliminate the nuclear stockpiles of both the U.S. and the Soviet Union over a ten-year period, but the deal collapsed due to disagreements regarding SDI development. Reagan attacked Gorbachev in a 1987 speech delivered in West Berlin, but negotiations continued. Gorbachev and Reagan broke the impasse by agreeing to negotiate separate treaties on
Treaty on Conventional Armed Forces in Europe the establishment of an effective verification system. Meanwhile, in December the INF Treaty between the United States and the Soviet Union was signed, effectively allowing mutual inspections. During the May–June 1988 Moscow Summit, US President Ronald Reagan and General Secretary Gorbachev emphasized the importance of stability and security in Europe, specifically calling for data exchange, verification of these data, and then reductions. In December Gorbachev announced at the United Nations a unilateral withdrawal of 50,000 troops from Eastern Europe, and demobilization of 500,000 Soviet troops. In January 1989, NATO and the Warsaw Treaty members produced the Mandate for the Negotiation