Gorbachev arrived at Reykjavik intending to put a significant disarmament package on the table, contingent on Reagan’s agreement to slow down the development of space weapons. In fact, Gorbachev’s proposal was essentially the one he had originally proposed in the run-up to the Geneva summit: a 50 percent cut in the ICBMs that were the core of the Soviet nuclear arsenal and the total elimination of intermediate-range missiles in Europe. But now Gorbachev was willing to treat limited research on space-based missile defense as compatible with the Anti-Ballistic Missile Treaty. The United States had only to agree to confine its SDI research to the laboratory for ten years and commit not to withdraw from the ABM Treaty for five years after that.
Over dinner with his advisers, Reagan returned to the even more sweeping idea that he’d raised previously: why not the complete elimination of ballistic missiles? The next day, with Gorbachev, the sky was the limit. When the Americans laid all their ICBMs on the table, Gorbachev called and raised by proposing the elimination of all strategic nuclear weapons, including submarines and bombers, over ten years. His bid was still contingent on ten years of adherence to his narrow interpretation of the ABM Treaty and its limits on missile defense, but he indicated he’d be willing to negotiate on that point.
more here.