relations Mikhail Gorbachev came to power in 1985. Although the Soviets did not accelerate military spending in response to Reagan's military buildup, their enormous military expenses, in combination with collectivized agriculture and inefficient planned manufacturing, were a heavy burden for the Soviet economy. At the same time, the prices of oil, the primary source of Soviet export revenues, fell to one third of the previous level in 1985. These factors contributed to a stagnant economy during Gorbachev's tenure. Reagan's foreign policy towards the Soviets wavered between brinkmanship and cooperation. Reagan appreciated Gorbachev's revolutionary change in the direction of the Soviet policy and shifted to diplomacy, intending to encourage him to pursue substantial arms agreements. They held four summit conferences between 1985 and 1988. Reagan believed that if he could persuade the Soviets to allow for more democracy and free speech, this would lead to reform and the end of communism. The critical summit was in Reykjavík in 1986, where they agreed to abolish all nuclear weapons. However, Gorbachev added the condition that SDI research must be confined to laboratories during the ten-year period when disarmament would take place. Reagan refused, stating that it was defensive only and that he would share the secrets with the Soviets, thus failing to reach a deal. In June 1987, Reagan addressed Gorbachev during a speech at the Berlin Wall, demanding that he "tear down this wall". The remark was ignored at the time, but after the wall fell in November 1989, it was retroactively recast as a soaring achievement. In December 1987, Reagan and Gorbachev met again at the Washington Summit to sign the Intermediate-Range Nuclear Forces Treaty, committing to the total abolition of their respective short-range and medium-range missile stockpiles. The treaty established an inspections regime designed to ensure that both parties honored the agreement. In May 1988, the U.S. Senate overwhelmingly voted in favor of ratifying the treaty, providing a major boost to Reagan's popularity in the aftermath of the Iran–Contra affair. A new era of trade and openness between the two powers commenced, and the United States and Soviet Union cooperated on international issues such as the Iran–Iraq War. Post-presidency (1989–2004) After leaving the presidency on January 20, 1989, Ronald and Nancy Reagan settled in a home in Bel Air, in addition to Rancho del Cielo in Santa Barbara. He received multiple awards and honors, and regularly attended Bel Air Church.