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

Mikhail Sergeyevich Gorbachev (born 2 March 1931) is a Russian and former Soviet politician. The eighth and final leader of the Soviet Union, he was the General Secretary of the Communist Party of the Soviet Union from 1985 until 1991. He was also the country's head of state from 1988 until 1991, serving as the chairman of the Presidium of the Supreme Soviet from 1988 to 1989, chairman of the Supreme Soviet from 1989 to 1990, and president of the Soviet Union from 1990 to 1991. Ideologically, Gorbachev initially adhered to MarxismLeninism although he had moved towards social democracy by the early 1990s.

Gorbachev was born in Privolnoye, Stavropol Krai, to a poor peasant family of Russian and Ukrainian heritage. Growing up under the rule of Joseph Stalin, in his youth he operated combine harvesters on a collective farm before joining the Communist Party, which then governed the Soviet Union as a one-party state according to the prevailing interpretation of MarxistLeninist doctrine. While studying at Moscow State University, he married fellow student Raisa Titarenko in 1953 prior to receiving his law degree in 1955. Moving to Stavropol, he worked for the Komsomol youth organization and, after Stalin's death, became a keen proponent of the de-Stalinization reforms of Soviet leader Nikita Khrushchev. He was appointed the First Party Secretary of the Stavropol Regional Committee in 1970, in which position he oversaw construction of the Great Stavropol Canal. In 1978, he returned to Moscow to become a Secretary of the party's Central Committee, and in 1979 joined its governing Politburo. Within three years of the death of Soviet leader Leonid Brezhnev, following the brief regimes of Yuri Andropov and Konstantin Chernenko, the Politburo elected Gorbachev as General Secretary, the de facto head of government, in 1985.

Although committed to preserving the Soviet state and to its socialist ideals, Gorbachev believed significant reform was necessary, particularly after the 1986 Chernobyl disaster. He withdrew from the SovietAfghan War and embarked on summits with United States president Ronald Reagan to limit nuclear weapons and end the Cold War. Domestically, his policy of glasnost ("openness") allowed for enhanced freedom of speech and press, while his perestroika ("restructuring") sought to decentralize economic decision-making to improve efficiency. His democratization measures and formation of the elected Congress of People's Deputies undermined the one-party state. Gorbachev declined to intervene militarily when various Eastern Bloc countries abandoned MarxistLeninist governance in 19891990. Internally, growing nationalist sentiment threatened to break up the Soviet Union, leading MarxistLeninist hardliners to launch the unsuccessful August Coup against Gorbachev in 1991. In the wake of this, the Soviet Union dissolved against Gorbachev's wishes and he resigned. After leaving office, he launched his Gorbachev Foundation, became a vocal critic of Russian presidents Boris Yeltsin and Vladimir Putin, and campaigned for Russia's social-democratic movement.

Widely considered one of the most significant figures of the second half of the 20th century, Gorbachev remains the subject of controversy. The recipient of a wide range of awards, including the Nobel Peace Prize, he was widely praised for his pivotal role in ending the Cold War, introducing new political freedoms in the Soviet Union, and tolerating both the fall of MarxistLeninist administrations in eastern and central Europe and the reunification of Germany. Conversely, he is often derided in Russia for accelerating the Soviet dissolution, an event which brought a decline in Russia's global influence and precipitated an economic collapse.

The Soviet Union, officially the Union of Soviet Socialist Republics (USSR), was a communist state that spanned Eurasia from 1922 to 1991. It was nominally a federal union of multiple national republics; in practice its government and economy were highly centralized until its final years. The country was a one-party state (prior to 1990) governed by the Communist Party of the Soviet Union, with Moscow as its capital within its largest and most populous republic, the Russian SFSR. Other major urban centers were Leningrad (Russian SFSR), Kiev (Ukrainian SSR), Minsk (Byelorussian SSR), Tashkent (Uzbek SSR), Alma-Ata (Kazakh SSR) and Novosibirsk (Russian SFSR). It was the largest country in the world, covering over 22,402,200 square kilometres (8,649,500 sq mi), and spanning eleven time zones.

The Soviet Union had its roots in the October Revolution of 1917 when the Bolsheviks, headed by Vladimir Lenin, overthrew the Provisional Government that had earlier replaced the house of Romanov of the Russian Empire. They established the Russian Soviet Republic, the world's first constitutionally guaranteed socialist state. Tensions escalated into a civil war between the Bolshevik Red Army and many anti-Bolshevik forces across the former Empire, among whom the largest faction was the White Guard. The White Guard engaged in violent anti-communist repression against the Bolsheviks and suspected worker and peasant Bolsheviks known as the White Terror. The Red Army expanded and helped local Bolsheviks take power, establishing soviets, repressing their political opponents and rebellious peasants through Red Terror. By 1922, the balance of power had shifted and the Bolsheviks had emerged victorious, forming the Soviet Union with the unification of the Russian, Transcaucasian, Ukrainian and Byelorussian republics. Upon the conclusion of the civil war Lenin's government introduced the New Economic Policy, which led to a partial return of a free market and private property; this resulted in a period of economic recovery.

Following Lenin's death in 1924, Joseph Stalin came to power. Stalin suppressed all political opposition to his rule inside the Communist Party and inaugurated a command economy. As a result, the country underwent a period of rapid industrialization and forced collectivization, which led to significant economic growth, but also led to a man-made famine in 1932–1933. The Gulag labour camp system was also expanded in this period. Stalin also fomented political paranoia and conducted the Great Purge to remove his actual and perceived opponents from the Party through mass arrests of military leaders, Communist Party members, and ordinary citizens alike, who were then sent to correctional labor camps or sentenced to death.

On 23 August 1939, after unsuccessful efforts to form an anti-fascist alliance with Western powers, the Soviets signed a non-aggression pact with Nazi Germany. After the start of World War II, the formally neutral Soviets invaded and annexed territories of several Eastern European states, including the eastern regions of Poland, Lithuania, Latvia and Estonia. In June 1941 the Germans invaded, opening the largest and bloodiest theater of war in history. Soviet war casualties accounted for the majority of Allied casualties of the conflict in the process of acquiring the upper hand over Axis forces at intense battles such as Stalingrad. Soviet forces eventually captured Berlin and won World War II in Europe on 9 May 1945. The territory overtaken by the Red Army became satellite states of the Eastern Bloc. The Cold War emerged in 1947, where the Eastern Bloc confronted the Western Bloc, which would unite in the North Atlantic Treaty Organization in 1949.

Following Stalin's death in 1953, a period known as de-Stalinization and the Khrushchev Thaw occurred under the leadership of Nikita Khrushchev. The country developed rapidly, as millions of peasants were moved into industrialized cities. The USSR took an early lead in the Space Race with the first ever satellite and the first human spaceflight and the first probe to land on another planet, Venus. In the 1970s, there was a brief détente of relations with the United States, but tensions resumed when the Soviet Union deployed troops in Afghanistan in 1979. The war drained economic resources and was matched by an escalation of American military aid to Mujahideen fighters.

In the mid-1980s, the last Soviet leader, Mikhail Gorbachev, sought to further reform and liberalize the economy through his policies of glasnost and perestroika. The goal was to preserve the Communist Party while reversing economic stagnation. The Cold War ended during his tenure and in 1989, Warsaw Pact countries in Central and Eastern Europe overthrew their respective Marxist-Leninist regimes. Strong nationalist and separatist movements broke out across the USSR. Gorbachev initiated a referendum—boycotted by Lithuania, Latvia, Estonia, Armenia, Georgia, and Moldova — which resulted in the majority of participating citizens voting in favor of preserving the Union as a renewed federation. In August 1991, a coup d'état was attempted by Communist Party hardliners. It failed, with Russian President Boris Yeltsin playing a high-profile role in facing down the coup. The main result was the banning of the Communist Party. The republics, led by Russia and Ukraine, declared independence. On 25 December 1991, Gorbachev resigned. All the republics emerged from the dissolution of the Soviet Union as independent post-Soviet states. The Russian Federation (formerly the Russian SFSR) assumed the Soviet Union's rights and obligations and is recognized as its continued legal personality in world affairs.

The Soviet Union produced many significant social and technological achievements and innovations regarding military power. It boasted the world's second-largest economy and the largest standing military in the world. The USSR was recognized as one of the five nuclear weapons states. It was a founding permanent member of the United Nations Security Council as well as a member of the OSCE, the WFTU and the leading member of the Council for Mutual Economic Assistance and the Warsaw Pact.

Before its dissolution, the USSR had maintained its status as a superpower, alongside the United States, for four decades after World War II. Sometimes also called "Soviet Empire", it exercised its hegemony in East-Central Europe and worldwide with military and economic strength, proxy conflicts and influence in developing countries and funding of scientific research, especially in space technology and weaponry.