AUG 31: Mr Gorbachev, who took power in 1985, opened up the then-USSR to the world and introduced a set of reforms at home.
But he was unable to prevent the slow collapse of the Soviet Union, from which modern Russia emerged.
Tributes have been paid worldwide, with UN chief Antonio Guterres saying he "changed the course of history".
"Mikhail Gorbachev was a one-of-a kind statesman," UN Secretary General Mr Guterres wrote in a Twitter tribute. "The world has lost a towering global leader, committed multilateralist, and tireless advocate for peace."
The hospital in Moscow where he died said he had been suffering from a long and serious illness.
In recent years his health has been in decline and he had been in and out of hospital. In June, international media reported that he had been admitted after suffering from a kidney ailment, though his cause of death has not been announced.
Russian President Vladimir Putin has expressed his deepest condolences following Mr Gorbachev's death, his spokesman Dmitry Peskov told Russian news agency Interfax, according to Reuters.
US President Joe Biden called him a "rare leader" and praised Mr Gorbachev as a unique politician who had the "imagination to see that a different future was possible" amid the tensions of the Cold War.
European Union President Ursula von der Leyen praised him as a "trusted and respected leader" who "opened the way for a free Europe".
"This legacy is one we will not forget," she added.
UK Prime Minister Boris Johnson said he admired Mr Gorbachev's courage and integrity, adding: "In a time of Putin's aggression in Ukraine, his tireless commitment to opening up Soviet society remains an example to us all."
Mr Gorbachev became general secretary of the Soviet Communist Party, and de facto leader of the country, in 1985.
At the time, he was 54 - the youngest member of the ruling council known as the Politburo, and was seen as a breath of fresh air after several ageing leaders. His predecessor, Konstantin Chernenko, had died aged 73 after just over a year in office.
Few leaders have had such a profound effect on the global order, but Mr Gorbachev didn't come to power seeking to end the Soviet grip over eastern Europe. Rather, he hoped to revitalise its society.
The Soviet economy had been struggling for years to keep up with the US and his policy of Perestroika sought to introduce some market-like reforms to the state run system.
Internationally he reached arms control deals with the US, refused to intervene when eastern European nations rose up against their Communist rulers and ended the bloody Soviet war in Afghanistan that had raged since 1979.
Meanwhile, his policy of glasnost, or openness, allowed people to criticise the government in a way which had been previously unthinkable.
But it also unleashed nationalist sentiments in many regions of the country which eventually undermined the stability of the country and led to its collapse.
In 1991, after a shambolically organised coup by communist hardliners failed, Mr Gorbachev agreed to dissolve the Soviet Union and left office.
He is seen in the West as an architect of reform who created the conditions for the end of the Cold War in 1991 - a time of deep tensions between the Soviet Union and Western nations, including the US and Britain.
He was awarded the Nobel Peace Prize in 1990 "for the leading role he played in the radical changes in East-West relations".
But in the new Russia that emerged after 1991 he has been on the fringes of politics, focusing on educational and humanitarian projects.
Mr Gorbachev made one ill-fated attempt to return to political life in 1996, receiving just 0.5% of the vote in presidential elections.
His divisive legacy is reflected in the tributes that followed his death.
Henry Kissinger, who served as US Secretary of State under President Richard Nixon, told the BBC's Newsnight programme that Mr Gorbachev will be "remembered in history as a man who started historic transformations that were to the benefit of mankind and to the Russian people".
James Baker, who negotiated the reunification of Germany with Mr Gorbachev's government, told the New York Times that "history will remember Mikhail Gorbachev as a giant who steered his great nation towards democracy".
But many Russians never forgave him for the turmoil that followed the collapse of the USSR.
Vladimir Rogov, a Russian-appointed official in occupied Ukraine, said Mr Gorbachev had "deliberately led the (Soviet) Union to its demise" and called him a traitor.
He will be buried in Moscow's Novodevichy cemetery, the resting place of many prominent Russians, next to his wife Raisa who died of leukaemia in 1999, Tass news agency said.
It was a busy day of international diplomacy, with several major summits that saw leaders from around the world displaying solidarity with Ukraine.
The Nato defensive alliance, as well as the EU and the G7 group of the world's richest nations held unprecedented emergency summits in Brussels.
Unity and support for Ukraine were the key themes, with leaders pledging military and humanitarian assistance.
Russia, meanwhile, accused the West of wanting the conflict to continue.
"The single most important thing is for us to stay unified and the world to continue to focus on what a brute [Vladimir Putin] is," US President Joe Biden told reporters.
"Putin has already crossed the red line into barbarism," UK Prime Minister Boris Johnson said.
One of the main takeaways of the day came from the Nato defensive alliance, which approved major increases of forces in Eastern Europe.
Four new battlegroups will be sent to Slovakia, Hungary, Bulgaria and Romania.
The group has never been more united which is "the opposite of what [Putin] intended", Mr Biden said.
World leaders also warned that if Russia were to use chemical or nuclear weapons they would be forced to respond. They weren't, however, willing to say what that response would look like.
Ukraine can win this war, Johnson says
One of those in Brussels today was Prime Minister Boris Johnson, who announced that the UK would send 6,000 missiles to Ukraine.
He also pledged £25m ($32m) in aid to help pay its soldiers' salaries.
"I think [Putin] had literally no idea that the Ukrainians were going to mount the resistance that they are," Mr Johnson told BBC Newsnight.
"He totally misunderstood what Ukraine is - and, far from extinguishing Ukraine as a nation, he's solidified it."
War in Ukraine: What Ukraine is getting right
One month into this invasion and so far, Ukraine has defied the odds. Outnumbered on almost every metric - in tanks, in troops, in aircraft - Ukraine's forces, reinforced by citizen volunteers, have in many places fought the Russian army to a standstill.
They have lost territory, especially in the south around Crimea, which was already occupied and annexed by Russia in 2014. But Moscow's original aim of quickly seizing the capital Kyiv and other major cities, forcing the government to resign, has manifestly failed.
The tide could still turn against Ukraine. Its forces are running dangerously low on the vital western-supplied anti-tank and anti-aircraft missiles needed to fend off the advancing Russians.
Many of Ukraine's most battle-hardened regular forces in the east of the country are at risk of being surrounded, cut off and annihilated. And with a quarter of the nation's population having fled their homes, those that stay put risk seeing their cities turned into a dystopian wasteland by relentless Russian artillery and rocket fire.
Yet despite these factors, Ukraine's forces are outperforming Russia's in this war, on several levels. This week the Pentagon spokesman John Kirby praised them as defending parts of their country "very smartly, very nimbly, very creatively". So what exactly have been the secrets of their success?
1. Highly motivated
There is a wealth of difference between the morale of the two armies. Ukrainians are fighting for the very survival of their country as a sovereign nation, appalled at President Putin's eve-of-war speech in which he said Ukraine was basically just an artificial Russian creation.
Ukrainians have rallied behind their government and their president. This has resulted in citizens with no prior military experience readily taking up arms to defend their towns and cities despite the overwhelming Russian firepower facing them.
"This is how people fight for their very existence," says Brigadier Tom Foulkes, who spent 35 years as a British Army officer in Germany during the Cold War. "This is how they defend their homeland and their families. Their courage is both shocking and splendid."
In practice this has freed up Ukrainian soldiers to go and fight on the front line, knowing their cities have defence in depth.
By contrast, many of the Russian soldiers sent to fight in Ukraine are conscripts just out of school, bewildered and confused at finding themselves in a war zone when they thought they were just going on an exercise.
Most had little or no battle preparation for the ferocity of the fighting they have encountered. There have been reports of desertions, food shortages and looting.
2. Command and control
Early expectations of a devastating Russian cyber attack, knocking out Ukraine's communications, did not materialise. Instead, Ukraine has somehow managed to maintain effective co-ordination over several battlefronts, even where it has lost ground.
Its government has stayed put in Kyiv and remained highly visible, with even the deputy prime minister dressed in a utilitarian khaki T-shirt as she addresses the nation against a backdrop of government insignia.
The Russian army, by contrast, does not appear to have any kind of unified leadership, with little co-ordination between its separate battlefronts.
This is likely to have had a negative effect on Russian military morale. It has been suggested the reported deaths of at least five Russian generals is partly a result of their having to get close to the fighting to dislodge their troops from getting bogged down.
At the level of Non-Commissioned Officers (NCOs), ie the corporals and the sergeants, Russian military doctrine allows for almost no initiative, with these junior ranks always waiting for orders from above.
Prof Michael Clarke, a military expert at King's College London, says Russian NCOs are beset with corruption and inefficiency and are deeply unpopular with those they command.
3. Sound tactics
Ukraine's forces are heavily outnumbered and yet they have made much better use of the ground and their weapons than the invading Russians.
Whereas the Russians have tended to concentrate their forces in slow, heavy armoured columns, often with vehicles bunched up close together, the Ukrainians have successfully conducted finely-tuned hit-and-run raids, sneaking up and firing off an anti-tank missile, then vanishing before the Russians can return fire.
Prior to the invasion, Nato trainers from the US, UK and Canada spent long periods in Ukraine, bringing its forces up to speed in defensive warfare and instructing them on how to make best use of state-of-the-art missile systems such as the Javelin or the Swedish-designed NLAW anti-tank weapon or the latest version of the Stinger anti-aircraft missile.
"The Ukrainians have been much cleverer than the Russians", says Prof Clarke, "because they've fought something much closer to a combined arms operation which the Russians haven't". By this he means they have made full use of all the military tools at their disposal, such as drones, artillery, infantry, tanks and electronic warfare.
When combined together, the sum of all these different aspects of warfare can create an exponential effect greater than the sum of its parts.
Another military strategist, Justin Crump, who runs the intelligence consultancy Sibylline, says Ukrainians have been particularly adept at seeking out the vulnerable points in Russian formations and hitting them hard. "Ukraine has made use of highly effective tactics", he says, including targeting Russian weak points such as supply convoys, using Nato-supplied weapon systems to good effect against precision targets and improvising where required.
While it is hard to get an accurate picture of casualty figures, even the more conservative estimates made by the Pentagon put Russian combat deaths at more than 7,000. That is nearly half as many men as the Soviets lost in 10 years of fighting in Afghanistan and we are only a month into this war.
Brig Tom Foulkes also has an explanation as to why so many Russian generals are getting killed on the front line: "This sounds to me like a deliberate and highly successful sniper campaign which could degrade the Russian command structures."
4. The Info War
And then there is the information war. Ukraine is winning this hands-down in most of the world - although not in Russia where the Kremlin still controls access to most of the media.
"Ukraine has mobilised the information sphere to tremendous domestic and international advantage", says Justin Crump. "This has come from the top down, aided by (President) Zelensky's formidable media savvy."
It's a view echoed by Dr Ruth Deyermond, senior lecturer in post-Soviet studies at Kings College London. "Clearly the Ukrainian government has been very successful in controlling the narrative about the war, certainly for the wider world," she says. "What the conflict has done for Ukraine's international reputation is absolutely remarkable."
But right now, one month into this desperate life-and-death struggle on Europe's eastern borders, that may still not be enough to salvage Ukraine.
The numerical might of the Russian army, for all its shortcomings, is not in Ukraine's favour. If somehow the supply of defensive weapons systems from the West dries up then there could only be so much longer this beleaguered nation can hold out.
LONDON, August 23: Britain said Monday it would urge the United States at a virtual G7 summit to extend an end-of-the-month deadline to complete evacuations of Western citizens and Afghan colleagues from Kabul.
US President Joe Biden has set an August 31 deadline for the chaotic airlift organised by thousands of temporarily deployed US troops but has left the door open to an extension if needed.
Armed forces minister James Heappey and other UK officials told British media that they would push for an extension at Tuesday's online leaders meeting of the G7 group of wealthy nations while acknowledging that the Taliban would have a crucial say now that they control Afghanistan.
Heappey said it is a "hard reality" that the evacuations from Afghanistan's capital could only be maintained beyond August 31 if led by the United States.
"Whether or not the US can be persuaded to stay is a matter for the prime minister (Boris Johnson) tomorrow in the G7 meeting," Heappey told Sky News, referring to an extension of the deadline.
Britain currently chairs the G7, also comprising Canada, France, Germany, Italy, Japan and the United States.
"I think everybody has to be clear that this is not just a discussion that happens between G7 leaders tomorrow, it is a discussion which happens with the Taliban," he added.
"The Taliban will have a choice, they can either seek to engage with the international community and show that they want to be a part of the international system.
"Or they can turn around and say there is no opportunity for an extension."
Foreign Office minister James Cleverly told BBC Radio Sunday night that his government would appeal for the extension at the G7.
"Obviously the more time that we've got, the more people we can evacuate and that's what we're pushing for," Cleverly said.
Britain, which has deployed 1,000 soldiers to aid its airlift efforts, is pushing for longer to get everybody out who qualifies, with the trans-Atlantic allies' defence ministers speaking by phone Sunday.
London has so far evacuated 5,725 people from Kabul since August 13, including more than than 3,100 Afghans and their families, according to the Ministry of Defence.
Heappey said early Monday it expects a further nine flights to depart over the next 24 hours.
He told Times radio that Afghans who are eligible for asylum in the West were also fleeing the country overland and showing up at embassies in neighbouring countries like Pakistan.
Just over a week, the Taliban, which the United States overthrew in 2001, went from winning control of its first provincial capital to taking over Kabul, capital of the war-torn Asian country.
LONDON, Aug. 17: British Prime Minister Boris Johnson and U.S. President Joe Biden spoke via phone Tuesday evening about the current situation in Afghanistan following Taliban takeover, Downing Street said in a statement.
The two leaders welcomed their countries' cooperation in recent days to help evacuate their nationals, current and former staff, and others from Afghanistan, it said.
"They resolved to continue working closely together on this in the days and weeks ahead to allow as many people as possible to leave the country," it added.
Johnson and Biden also agreed on the need for the global community to come together to prevent a humanitarian crisis in Afghanistan.
Britain's plans include increased humanitarian aid to the region and resettlement of refugees, it said.
Britain's Home Office said on Tuesday night that up to 20,000 Afghan refugees will be offered a route to set up homes in Britain over five years.
In their phone conversation, the two leaders also agreed to hold a virtual Group of Seven (G7) leaders' meeting in the coming days to discuss the Afghanistan situation.
In a televised speech on Monday, Biden stood by his decision to withdraw U.S. troops from Afghanistan while acknowledging Kabul's collapse to the Taliban came much sooner than Washington had anticipated.
Just over a week, the Taliban, which the United States overthrew in 2001, went from winning control of its first provincial capital to taking over Kabul, capital of the war-torn Asian country.
Johnson said on Sunday that the U.S. decision to pull out of Afghanistan has "accelerated things."
LONDON, May 5: Foreign ministers from the Group of Seven wealthy industrialized nations gathered Tuesday in London for their first face-to-face meeting in more than two years, with the issue of whether to challenge or coax a surging China high on the agenda.
Host nation Britain is keen to show that the rich countries' club still has clout in a fast-changing world, and has warned that the increasingly aggressive stances of Russia, China and Iran pose a challenge to democratic societies and the international rule of law.
U.K. Foreign Secretary Dominic Raab said the meeting “demonstrates diplomacy is back.”
U.S. Secretary of State Antony Blinken underscored the United States' re-embrace of its international allies since President Joe Biden replaced his “America-first” predecessor, Donald Trump.
Blinken said engaging with China “from a position of strength ... means actually working with allies and partners, not disparaging them.”
“It means leaning in and engaging in the vast array of multilateral and international organizations because that’s where so many of the rules are made. That’s where the norms are shaped," he said. “And if we’re not leaning in, we know that Beijing is likely to be trying to do so in our place.”
At the two-day meeting, top diplomats from the U.K., the United States, Canada, France, Germany, Italy and Japan also were to discuss the military coup in Myanmar, the humanitarian crisis in Syria, the Tigray crisis in Ethiopia and the precarious situation in Afghanistan, where U.S. troops and their NATO allies are winding down a two-decade deployment.
The U.K. Foreign Office said the group would also discuss “Russia’s ongoing malign activity,” including Moscow's earlier troop buildup on the border with Ukraine and the imprisonment of opposition politician Alexei Navalny.
While the G-7 members likely can agree in broad terms to condemn Navalny's imprisonment or Beijing's repression of the Uyghur minority in Xinjiang, there are differences over how to relate to countries such as China and Russia that will have to be smoothed out in any final communique on Wednesday.
Asked what message the group would send to authoritarian regimes, Raab said the G-7 believed “in keeping trade open. We believe in standing up for open societies, for human rights and democracy. We believe in safeguarding and promoting public good.”
The G-7 ministers will also try to agree on a way to make coronavirus vaccines available around the globe in the long term. But for now, wealthy countries are reluctant to give up precious stocks until they have inoculated their own people.
The ministers wore face masks and greeted one another with arm and elbow bumps as they arrived at Lancaster House, a grand former stately home in central London. Plastic screens between participants and on-site coronavirus tests were among measures intended to make the venue COVID-secure.
The British government, which holds the G-7 presidency this year, invited the foreign ministers of Australia, India, South Korea and South Africa to join parts of the meeting, including Tuesday evening's formal dinner. The guest list was intended to underline the G-7’s support for democracies, as well as the U.K. government’s attempts to build stronger ties with Asia in the wake of the country’s departure from the European Union.
Britain's Conservative-led government hopes the resumption of in-person G-7 meetings — after more than a year of disruption by the coronavirus pandemic — will give the group a jolt of energy and bolster attempts to forge a post-Brexit “Global Britain” role for the U.K.
Prime Minister Boris Johnson is set to host the other G-7 leaders at a summit in Cornwall, England, in June.
Opposition politicians and international aid organizations say the goal of Britain playing a bigger role in world affairs is undermined by the government's decision to slash its foreign aid budget from 0.7% of gross domestic product to 0.5% because of the economic hit from the pandemic.
Raab said the aid cuts were a “difficult decision” but insisted Britain would become “an even greater force for good in the world.”
