Union of Soviet Socialist Republics (USSR, 1917-1991).
The Molotov-Ribbentrop pact, was a non-aggression treaty between Nazi Germany and the Soviet Union. It was signed in Moscow on August 23, 1939 by the Soviet foreign minister Vyacheslav Molotov and German foreign minister Joachim von Ribbentrop. Secret Additional Protocol:
The pact was announced as a non-aggression pact, but in a secret appendix Eastern Europe was divided into German and Soviet spheres of influence. Finland, Estonia, Latvia, Lithuenia and Bessarabia were apportioned to the Soviet sphere. Poland was to be partitioned in the event of its "political rearrangement", the areas east of the rivers Narev, Vistula and San going to the Soviet Union while Germany would occupy the west.
On September 28th 1939, the three Baltic States were given no choice but to sign a so-called Pact of defence and mutual assistance, which permitted the Soviet Union to station troops in Estonia, Latvia and Lithuania.
Stalin had succeeded in attaining a Soviet military presence in the Baltic States. Stalin�s true intentions were to annex Latvia, Lithuania, and Estonia into the Soviet Union. To achieve annexation, Stalin accused the Balts of conspiring to form a military alliance against the Red Army. Stalin used this as a catalyst to order heavily armed Soviet troops to stream into the Baltic States and crush all resistance.
The dilemma faced by these countries can be best portrayed by statement given by the Polish commander in chief, Marshal Edward Rydze-Smigly, upon his refusal to allow Soviet troop movements within Poland, "With the Germans we run the risk of loosing our liberty. With the Russians we will loose our soul."
The Soviet secret police, NKVD began operations in June of 1940. An average of two to three hundred people per month disappeared without a trace. Mostly senior civil servants, top army officers and intellectuals. They were sent to concentration camps or to Siberia, many are thought to have died in the camps. By June 22, 1941, civilian losses due to deportation, mobilizations, and massacres stood at sixty thousand in Estonia, thirty-five thousand in Latvia, and thirty-four thousand in Lithuania.
There always was a state security service within the Soviet Union. From the very birth of the Soviet state. In December of 1917 the Cheka, an acronym for the All-Russian Extraordinary Commission for Combating Counter-Revolution and Sabotage, was established. By 1918 under the rule of die-hard Polish Bolshevik Felix Derzhinsky the Cheka became the most feared institution in the whole corse of the Russian Civil War. The Cheka executed men women and children under any suspicions whatsoever.
Collapse
In August 1991, communist hardliners tried a death-or-glory tactic to save the Soviet Union - seizing power by force. Their coup failed and the Soviet Union was dead within months.
But the chain of events leading to the collapse was set in motion six years earlier, when Politburo member Mikhail Gorbachev became Soviet leader. He was only the sixth leader since the USSR's birth in 1922 - but his actions were to make him the last. He will introduce two Russian words to international vocabulary: "perestroika", meaning restructuring, and "glasnost", meaning openness.
Both concepts are revolutionary in Soviet terms - until now the system has been stagnant and closed.
But Gorbachev has no idea that the events he is setting in motion will bring about the collapse of an entire empire - and tear down the "Iron Curtain" which has divided Europe since the end of World War II.
Gorbachev appoints a little-known provincial party boss as head of the Moscow Communist Party. His name is Boris Yeltsin.
Gorbachev has already made another appointment which will prove significant - Eduard Shevardnadze, head of the Communist Party in the republic of Georgia. He has become foreign minister, replacing the veteran - and hardline - Andrei Gromyko.
Shervardnadze, like Gorbachev, believes in creating a more liberal and dynamic society. Both men have shared the vision for years. Now they are working together to bring it into effect.
Yeltsin, establishing himself in Moscow politics, also believes in change. As his new broom sweeps through Moscow's dusty politics, he begins sacking officials and axing privileges which party stalwarts have enjoyed for years.
In January and again in June, Gorbachev goes before the communists' Central Committee and proposes deep political and economic reforms. They include bringing a taste of democracy to some areas of society - including within the Communist Party. Perestroika is beginning in earnest.
By now the outside world is taking notice of the reformer, and wondering whether he can pull it off. His support inside and outside the USSR is high.
Perestroika moves from concept to best-seller, as Gorbachev publishes a book about his reforms in November. It goes on sale around the world.
But also in November, Yeltsin is forced out of his job as Moscow party boss. He has pushed for perestroika too far, too fast, and has criticised Gorbachev for moving too slowly.
The sacking leaves Yeltsin personally embittered against Gorbachev - a vital factor in future developments. Crucially for Yeltsin, Gorbachev allows him to stay on in Moscow, as deputy construction minister.
Perestroika hits its first major political iceberg. It has already been resisted by bureaucrats trying to block Gorbachev's economic reforms. Now, hardline communist newspaper Sovetskaya Rossiya publishes a clarion call for communists to resist Gorbachev's reforms. The call comes in a letter from a Leningrad chemist, Stalinist Nina Andreyeva, but Gorbachev is out of the country and hardliners are suspected of being behind it.
In the Baltic States, meanwhile, thoughts of independence are beginning to stir in the climate of change. In Estonia, the Popular Front is formed - a political party in all but name, even though only the Communist Party is allowed to exist. Latvia and Lithuania follow suit.
The first rumblings of inter-ethnic unrest are also felt, as clashes begin over Nagorno Karabakh in Azerbaijan, between Azeris and Armenians. Later, violence will also flare in Georgia, where North and South Ossetia and Abkhazia want independence.
Gorbachev marches on with perestroika and glasnost. He welcomes President Reagan to Moscow and later proposes a new presidency and elected parliament.
Elections are held for the new parliament set up as part of Gorbachev's reforms. It is called the Congress of People's Deputies. Boris Yeltsin wins a massive vote in a Moscow constituency - he is back in national politics.
Live television broadcasts of parliament later prove so popular they have to be taken off the air - because millions of workers are downing tools to watch.
Gorbachev has also pulled the last Soviet troops out of the deeply unpopular and costly war in Afghanistan. His popularity remains high.
But as the democrats celebrate the elections, the hardliners have their say. A fortnight after the elections, a peaceful demonstration in the republic of Georgia is broken up by Soviet troops. They have been ordered not to use live fire - so instead they use poisonous gas and sharpened shovels. Nineteen people, most of them women, are killed. Gorbachev denies all prior knowledge of events.
Gorbachev announces that countries in the Warsaw Pact are free to decide on their own futures. Lech Walesa's Solidarity movement has already trounced the communists in Poland in June elections. Walesa takes office in August.
Across Eastern Europe, people want change and are risking making their feelings known. Last time it was tried - in Hungary in 1956 and in Prague in 1968 - Soviet forces ruthlessly crushed the protests. This time, the will of the people prevails.
In September, Hungary stuns the world by opening its borders with the West - a previously unthinkable move, which in another era would have brought a crushing Soviet response.
Thousands of East Europeans climb into their communist-built Trabant cars to join a jubilant exodus to Austria. Perestroika overflows into the West
The Berlin Wall - the single most potent symbol of the Cold War - is torn down in an incredible display of "people power". Gorbachev could still use force to prop up his collapsing empire: the world watches as the wall is hacked away, waiting to see if he will act. He chooses not to. Scenes of joy are broadcast around the world as families and neighbours are united. Only months earlier those who tried it risked being shot.
Czechoslovakia is the next country to break free. The "Velvet Revolution" bloodlessly ousts the communists and installs playwright Vaclav Havel as president.
As the year draws to a close, Romanians also go for revolution. This time there is bloodshed, as riots erupt in the city of Timisoara, but the ruthless reign of President Ceausescu ends. He and his wife are executed on Christmas Day.
But as freedom is extended across the Soviet bloc, Gorbachev is becoming more unpopular at home. Shortages have worsened since his economic reforms began, and living standards are falling. Dissatisfaction with perestroika starts to take hold.
The old Soviet ways are dying but not dead. Moscow may have let the Warsaw Pact countries break free, but is not ready for Soviet republics to follow. The Baltic states are still most vociferous, and Gorbachev is trying to win their support for a looser but unmistakably Soviet federation.
In mid-January Soviet troops move in to break up demonstrations in Azerbaijan's capital, Baku. At least 100 people die - possibly many more.
But Gorbachev's reforms - and public clamour for faster change - keep moving. In February he responds to mass demonstrations by calling on parliament to allow multi-party politics - stripping the Communist Party of its monopoly on power under the notorious Article 6 of the constitution.
Perestroika also turns Gorbachev into the first - and only - Soviet president. Until now, all six Soviet leaders have been general secretaries of the Communist Party. Now, Gorbachev is voted president by the top echelon of parliament, the Supreme Soviet.
And the independence clamour has been growing. In January, Soviet troops acted against protesters in Lithuania and Latvia, killing about two dozen people - at least 13 of them in an operation to storm the television tower in the Lithuanian capital, Vilnius.
In March, a referendum on the Soviet Union's future found a majority wanted some kind of reformed union to be retained, but the Baltic states are still spearheading moves for a complete breakaway.
Yeltsin, after restoring his arch-rival to power, now sets about taking Gorbachev's world apart. Gorbachev - who has returned still believing in the Communist Party's future - is made to read out an account of his own people plotting against him. Yeltsin orders the Soviet Communist Party to end its activities on Russian soil.
The next day Gorbachev resigns as Soviet Communist Party general secretary and dissolves its Central Committee.
The Soviet Union is entering its final days.
The Baltic states - the first to have sown the seeds of independence - have been the first to reap the harvest. Moscow officially recognised their status as sovereign states on 6 September 1991.
Other republics have already begun moves to break away, or start them now. Ukraine, Armenia, Georgia and Moldova are among the first in the queue.
On 25 December, Gorbachev goes on television to announce he is stepping down as Soviet president. The Soviet flag is lowered from the Kremlin for the last time. The USSR is no more.
For several decades was locked in a bitter ideological Cold War with the United States.
"Collapsed" better described as fragmented into more well defined Monolithic Cultural Blocks.
The successive governments of the former Soviet Union, while arguably repressive and disrespectful of human rights did foster developement in the fields of science and technology. Victor Glushkov, for example, was a prominent world figure in the field of computer engineering museum.e-ukraine.org 
, Abram Ioffe, a renowned physicist.
After the declaration of independence by many of the states of the former Soviet Union, scientists, including computer scientists were free to emmigrate to seek opportunities elsewhere. One of these who took advantage of this opportunity was Alexey Pajitnov inventor of the Tetris Game, developed while he was a salaried employee at the Russian Academy of Sciences in Moscow.
See original on c2.com