Mark Stone, from Sky News, has tweeted this poignant image of Gorbachev with Ronald Reagan. Jonathan Eyal, of the think-tank the Royal United Services Institute, said: He [Gorbachev] didn’t believe that the Soviet Union was actually an empire in itself of nations that did not want to be shackled. Like all Soviet leaders, and dare I say like Russian leaders today, he saw the Soviet Union as synonymous with Russia and he simply could not understand why nations wanted to be independent. "He started historic transformations to benefit mankind" - Henry Kissinger Former US secretary of state Henry Kissinger said Gorbachev “performed great services” but was “not able to implement all of his visions”. He told BBC’s Newsnight: The people of eastern Europe and the German people, and in the end the Russian people, owe him a great debt of gratitude for the inspiration, for the courage in coming forward with these ideas of freedom. Kissinger, after again acknowledging Gorbachev was unable to implement his full vision, added: He will still be remembered in history as a man who started historic transformations that were to the benefit of mankind and to the Russian people. "A one-of-a-kind statesman who changed the course of history" - António Guterres António Guterres, secretary general of the United Nations, has described Gorbachev as a “towering leader”. Sir Keir Starmer, leader of the Labour party in England, said Mikhail Gorbachev was “one of the great figures” of last century” who will “forever be remembered”. Peter Baker, from the New York Times, has shared this tribute. His first public remarks on the Chernobyl nuclear power station disaster, delivered on Russian television on 14 May 1986, 18 days after the explosion. This is one more tolling of the bell, and a new terrible warning, that in the nuclear age what is needed is new political thinking and new policies. Some notable quotes from Mikhail Gorbachev. On meeting his wife Raisa (from an interview with US Vogue in 2013): One day we took each other by the hand and went for a walk in the evening. And we walked like that for our whole life. Arnold Schwarzenegger, the actor and former governor of California, has tweeted this tribute and photograph of himself with Gorbachev. In a 2011 interview with the Guardian, Gorbachev was asked to name the things he most regretted. He replied: The fact that I went on too long in trying to reform the Communist party. He should have resigned in April 1991, he said, and formed a democratic party of reform since the Communists were putting the brakes on all the necessary changes. His second regret, he said, is that he did not start to reform the Soviet Union and give more power to its 15 republics at an earlier stage. "Without him, it would not have been possible to end cold war peacefully" – Condoleezza Rice Condoleezza Rice, former US secretary of state, has posted a tribute on Twitter. Gorbachev was remembered fondly in the west, where he was referred to affectionately by the nickname Gorby and best known for defusing US-Soviet nuclear tensions in the 1980s as well as bringing eastern Europe out from behind the Iron Curtain. He won the Nobel Peace Prize in 1990 for negotiating a historic nuclear arms pact with the US president Ronald Reagan, and his decision to withhold the Soviet army when the Berlin Wall fell a year earlier was seen as key to preserving Cold War peace, AFP reports. He was also championed in the west for spearheading reforms to achieve transparency and greater public discussion that hastened the breakup of the Soviet empire. Boris Johnson "admired Gorbachev"s courage and integrity" The UK’s outgoing prime minister, Boris Johnson, said he is “saddened” to hear that Mikhail Gorbachev has died, in a “time of Putin’s aggression in Ukraine”. Putin’s press secretary Dmitry Peskov said in the morning the Russian president would send a telegram with condolences to the relatives and friends of the statesman. "A trusted and respected leader" – Ursula von der Leyen Ursula von der Leyen, president of the European Commission, has paid tribute on Twitter. Broadcaster and author John Simpson said he is “really sad” that the “decent” and “well-intentioned” former Soviet president Mikhail Gorbachev has died. In a Twitter post, Simpson, who interviewed Gorbachev, wrote: “Really sad that Mikhail Gorbachev has died: a decent, well-intentioned, principled man who tried to rescue the unrescuable.” He added: “In private he was charming and surprisingly amusing. It wasn’t his fault things went so wrong.” Vladimir Putin expresses condolences – Kremlin spokesman The Russian president Vladimir Putin expresses his deepest condolences on the death of Mikhail Gorbachev, a Kremlin spokesman told the Interfax news agency.