Use the quotes to answer the question.
· “Whoever does not miss the Soviet Union has no heart. Whoever wants it back has no brain.” - Vladimir Putin
· “It is difficult to violently suppress people in the long run, as the example of the Soviet Union and the Eastern European countries has shown.” - Dalai Lama
· “If you look at great human civilizations, from the Roman Empire to the Soviet Union, you will see that most do not fail simply due to external threats but because of internal weakness, corruption, or a failure to manifest the values and ideals they espouse.” - Cory Booker
Which event do all of these quotes relate?