Mikhail Gorbachev

Former Soviet Union President Mikhail Gorbachev speaks at a meeting with former U.S. President George Bush in Moscow, May 23, 2005.

Mikhail Gorbachev, then Soviet Politburo member, with British Prime Minister Margaret Thatcher at Chequers, Buckinghamshire, England, March 11, 1985.

Then Soviet leader Mikhail Gorbachev and then Cuban leader Fidel Castro wave from an open top car as it drives through Havana's Revolution Square, April 2, 1989.

This photo shows former U.S. President Ronald Reagan at his first meeting with former Soviet leader Mikhail Gorbachev in Geneva, Switzerland, 1985.

Then Russian President Boris Yeltsin and then Soviet President Mikhail Gorbachev touch hands during Gorbachev's address to the Extraordinary meeting of the Supreme Soviet of Russian Federation in Moscow, August 23, 1991.

Former Soviet leader Mikhail Gorbachev and his wife Raisa with former U.S. President Ronald Reagan and his wife Nancy, at the Reagan ranch near Santa Barbara, California, May 3, 1992.

Mikhail Gorbachev on a visit to Disneyland in Chiba, north of Tokyo, Japan, April 12, 1992.

Russian President Putin listens to former President of the Soviet Union Gorbachev during news conference in Schleswig, Germany, December 21, 2004.