Mikhail Gorbachev, who ended the Cold War without bloodshed but failed to prevent the collapse of the Soviet Union, died at the age of 91.

Afghan Voice Agency(AVA)_Monitoring, Gorbachev, the last Soviet president, forged arms reduction deals with the United States and partnerships with Western powers to remove the Iron Curtain that had divided Europe since World War Two and bring about the reunification of Germany.

But his internal reforms helped weaken the Soviet Union to the point where it fell apart, a moment that President Vladimir Putin has called the “greatest geopolitical catastrophe” of the twentieth century.

“Mikhail Gorbachev passed away tonight after a serious and protracted disease,” said Russia’s Central Clinical Hospital.

Putin expressed “his deepest condolences”, Kremlin spokesman Dmitry Peskov told Interfax. “Tomorrow he will send a telegram of condolences to his family and friends,” he said.

Putin said in 2018 he would reverse the Soviet Union’s disintegration if he could, Reuters quoted news agencies reported.

World leaders were quick to pay tribute. European Commission chief Ursula von der Leyen said Gorbachev, who was awarded the Nobel Peace Prize in 1990, had opened the way for a free Europe, Reuters reported.

U.S. President Joe Biden said he had believed in “glasnost and perestroika – openness and restructuring – not as mere slogans, but as the path forward for the people of the Soviet Union after so many years of isolation and deprivation.”

British Prime Minister Boris Johnson, citing Putin’s invasion of Ukraine, said Gorbachev’s “tireless commitment to opening up Soviet society remains an example to us all”.