During the first half of the 1980s the Soviet Economy ran out of steam, mainly because of fall in the oil markets, the main Soviet export commodity.
At the same time, the US have sharply increased their defense spending, and the Soviet leaders felt obliged to respond in kind.
As you may remember, the Afghan war was raging at the time, draining the little the USSR had of resources. The leaders in Kremlin ran out of ideas how to avoid a looming bankruptcy and picked fresh blood as a new General Secretary of the Communist Party of Soviet Union. It was the starry-eyed and bushy-tailed, smooth-talking 54-year old Mikhail Gorbachev.
In 1985 he launched an ambitious series of reforms that got the name of Perestroika. The events initiated by him consisted of:
Finding ways of mending relations with the West, because the arms race was bleeding the Soviets dry. Henceforth, the many summits with Western leaders, all smiles and big words and disarmament treaties. Soviet codename “New Thinking”.
Figuring out how to tell us, the proud Soviet citizens, why we no longer want death and destruction to Western Capitalism, but instead must find ourselves in a dialogue with our class enemies about everything normal people may want to talk about. As well as why it was now possible to criticize at least parts of what Communists had done and continued to do to our country. Soviet codename “Glasnost”.
Figuring out how to boost the national economy and release private initiative in a way that doesn´t rob the state bureaucracy of the unlimited control of everything that´s going on in the country. Soviet codename “Acceleration”.
All three projects ended in abject failure. It turned out that Gorbachev was a well-intentioned demagogue who had no idea of what he was doing. Modern Russians look back at that time with shame and incredulity. The best you can say about Perestroika is that it buried Communism, and relatively few people died.
Ethnic fault lines in the USSR vs. a range of German identities.
The experience from British and French colonies confirm that once you create local elite and give them Western education, their second generation starts thinking independence, and the third is downward anti-colonialist. The current heads of Kazakhstan and Tajikistan, for example, were on top of the ladder when the USSR broke apart, and that was generally the story everywhere apart from the Baltics and Georgia.
2. The USSR was a continuation of Russian empire under different color. Russians felt being taken advantage of, for the benefit of smaller, less developed nations. Germany is a national state with a high degree of solidarity.
Generally, imperial way of governing means equal opportunity for most ethnic groups within the empire. The core nation often is discriminated against, as monarchs seek safety making their court from a tight group of outsider minorities. Think of the Ottoman janissaries and Mamelukes in Egypt.
Russian Empire under Peter the Great started out as a colonial project of mainly Western meritocracy reigning over millions of Eastern Slav peasants. Ever since, Russians often felt an underdog nation, especially in the USSR (Stalin and many in the secret police were Georgian, the urban elite was dominated by Jews, the mob were typically ethnic gangs from the Caucasus and Central Asia). When Yeltsin broke out of the USSR, the national holiday he declared for the occasion was often called the Day of Independence.
(The subsequent years made Russians feel vindicated. Most of the new independent states sunk into chaos and poverty, while Russia has enjoyed a long streak of prosperity never seen in our history).
3. The USSR went bankrupt. Modern Germany is an undestructible machine of economic success.
The ethnic elites in the former USSR saw no sense in subjugating themselves to Moscow once the transfer of wealth ceased and the machine of imperial control ran out of steam. The Soviet economic model lost all attraction once the Chinese under Deng xiaoping showed they can do it much better.