Fraying amongst the members of the Warsaw Pact nations and instability of its western allies, first indicated by Lech Walesa's 1980 rise to leadership of the trade union Solidarity, accelerated, leaving the Soviet Union unable to depend upon its Eastern European satellite states for protection as a buffer zone. By 1989, Moscow had repudiated the Brezhnev Doctrine in favor of non-intervention in the internal affairs of its Warsaw Pact allies. Gradually, each of the Warsaw Pact nations saw their communist governments fall to popular elections and, in the case of Romania, a violent uprising. By 1991 the communist governments of Bulgaria, Czechoslovakia, East Germany, Hungary, Poland and Romania, all of which had been imposed after World War II, were brought down as revolution swept Eastern Europe.
The Soviet Union also began experiencing upheaval as the political consequences of glasnost reverberated throughout the country. Despite efforts at containment, the upheaval in Eastern Europe inevitably spread to nationalities within the USSR. In elections to the regional assemblies of the Soviet Union's constituent republics, nationalists as well as radical reformers swept the board. As Gorbachev had weakened the system of internal political repression, the ability of the USSR's central Moscow government to impose its will on the USSR's constituent republics had been largely undermined. Massive peaceful protests in the Baltic Republics such as The Baltic Way and the Singing Revolution drew international attention and bolstered independence movements in various other regions.
The rise of nationalism under freedom of speech soon reawakened simmering ethnic tensions in various Soviet republics, further discrediting the ideal of a unified Soviet people. One instance occurred in February 1988, when the government in Nagorno-Karabakh, a predominantly ethnic Armenian region in the Azerbaijan SSR, passed a resolution calling for unification with the Armenian SSR. Violence against local Azerbaijanis was reported on Soviet television, provoking massacres of Armenians in the Azerbaijani city of Sumgait.
...On February 7, 1990, the Central Committee of the Communist Party of the Soviet Union agreed to give up its monopoly of power. Over the next several weeks, the 15 constituent republics of the USSR held their first competitive elections. Reformers and ethnic nationalists won many of the seats.
The constituent republics began to assert their national sovereignty over Moscow and started a "war of laws" with the central government, wherein the governments of the constituent republics repudiated union-wide legislation where it conflicted with local laws, asserting control over their local economies and refusing to pay tax revenue to the central Moscow government. This strife caused economic dislocation as supply lines in the economy were severed, and caused the Soviet economy to decline further.
The pro-independence movement in the Lithuanian SSR, Sajudis, established on June 3, 1988, caused a visit by Gorbachev in January 1990 to the Lithuanian capital, Vilnius, which provoked a pro-independence rally of around 250,000 people.
On March 11, 1990, the Lithuanian SSR, led by Chairman of the Supreme Council Vytautas Landsbergis, declared restoration of independence. However, the Soviet Army attempted to suppress the movement. The Soviet Union initiated an economic blockade of Lithuania and kept troops there "to secure the rights of ethnic Russians."
On March 30, 1990, the Estonian Supreme Council declared Soviet power in Estonian SSR since 1940 to have been illegal, and started a process to reestablish Estonia as an independent state. The process of restoration of independence of the Latvian SSR began on May 4, 1990, with a Latvian Supreme Council vote stipulating a transitional period to complete independence.
On January 13, 1991, Soviet troops, along with KGB Spetsnaz Alpha Group, stormed the Vilnius TV Tower in Vilnius, Lithuania to suppress the nationalist media. This ended with 14 unarmed civilians dead and hundreds more injured. Later that month in Georgian SSR, anti-Soviet protesters at Tbilisi demonstrated support for Lithuanian independence.
On March 17, 1991, in a Union-wide referendum 76.4% of all voters voted for the retention of the Soviet Union in a reformed form. The Baltics, Armenia, Georgia and Moldova boycotted the referendum. In each of the other nine republics, a majority of the voters supported the retention of the renewed Soviet Union. Following the results, Armenia indicated it wanted to rejoin in Union discussion.
On June 12, 1991, Yeltsin won 57% of the popular vote in the democratic elections for the post of president of the Russian SFSR, defeating Gorbachev's preferred candidate, Nikolai Ryzhkov, who won 16% of the vote. In his election campaign, Yeltsin criticized the "dictatorship of the centre", but did not suggest the introduction of a market economy. Instead, he said that he would put his head on the railtrack in the event of increased prices. Yeltsin took office on July 10.
On the night of July 31, 1991, Russian OMON from Riga, the Soviet military headquarters in the Baltics, assaulted the Lithuanian border post in Medininkai and killed seven Lithuanian servicemen. This further weakened the Soviet Union's position, internationally and domestically.