1985    Mikhail Gorbachev becomes the Soviet Union's leader.

1985    Soviet leader Mikhail Gorbachev declares a moratorium on the deployment of middle-range missiles in Europe.

1985    Cold War: In Geneva, U.S. President Ronald Reagan and Soviet Union leader Mikhail Gorbachev meet for the first time.

1986    Cold War: U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev meet in Reykjavík, Iceland, in an effort to continue discussions about scaling back their intermediate missile arsenals in Europe.

1986    Mikhail Gorbachev, leader of the Soviet Union, releases Andrei Sakharov and his wife from internal exile in Gorky.

1987    Cold War: At the Brandenburg Gate U.S. President Ronald Reagan publicly challenges Mikhail Gorbachev to tear down the Berlin Wall.

1988    U.S. President Ronald Reagan begins his first visit to the Soviet Union when he arrives in Moscow for a superpower summit with Soviet leader Mikhail Gorbachev.

1989    Soviet leader Mikhail Gorbachev arrives in Havana, Cuba to meet with Fidel Castro in an attempt to mend strained relations.

1989    Cold War: In a meeting off the coast of Malta, US President George H. W. Bush and Soviet leader Mikhail Gorbachev release statements indicating that the cold war between their nations may be coming to an end.

1990    Mikhail Gorbachev is elected as the first executive president of the Soviet Union.

1990    George H. W. Bush and Mikhail Gorbachev sign a treaty to end chemical weapon production.

1990    Transnistria is unilaterally proclaimed a Soviet republic; the Soviet president Mikhail Gorbachev declares the decision null and void.

1990    Soviet Union leader Mikhail Gorbachev is awarded the Nobel Peace Prize for his efforts to lessen Cold War tensions and open up his nation.

1991    Collapse of the Soviet Union, August Coup: Soviet President Mikhail Gorbachev is placed under house arrest while on holiday in the town of Foros, Crimea.

1991    Collapse of the Soviet Union, August Coup: more than 100,000 people rally outside the Soviet Union's parliament building protesting the coup aiming to depose President Mikhail Gorbachev.

1991    Coup attempt against Mikhail Gorbachev collapses.

1991    Mikhail Gorbachev resigns as head of the Communist Party of the Soviet Union.

1991    Collapse of the Soviet Union – Mikhail Gorbachev resigns as Secretary of the Soviet Communist Party.

1991    Mikhail Gorbachev resigns as president of the Soviet Union (the union itself is dissolved the next day). Ukraine's referendum is finalized and Ukraine officially leaves the Soviet Union.