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No picture better tells the story of Russia's failed 1991 coup than that of a fist-pumping Boris Yeltsin defying Communist hard-liners from the top of a tank.

Those who were by Yeltsin's side describe his decision 20 years ago Friday to climb onto the tank as a stroke of political brilliance that proved crucial for the defeat of the coup. They also recall numerous other factors, some less known, that combined to give Yeltsin the victory he needed to become the undisputed leader of Russia as the Soviet Union collapsed.

Among those with Yeltsin was his top adviser Gennady Burbulis, who recently spoke to The Associated Press about those August days.

Few Russians today see Yeltsin as a hero, but in the summer of 1991 he had just been elected to the new post of Russian president in the first popular presidential vote. He held out the promise of a free and democratic Russia.

Soviet President Mikhail Gorbachev, who was struggling to keep the Soviet Union from splitting apart, gave his grudging approval to a plan to recognize the sovereignty of Russia and the other 14 Soviet republics in exchange for preserving a central government with limited powers. The new union treaty was to be signed Aug. 20.

Communist hard-liners in Gorbachev's government believed the treaty spelled the end of the Soviet Union and decided to act.

In the early hours of Aug. 19, they announced they were seizing power from Gorbachev, who they said was unable to carry out his duties because of poor health. In fact, he had been placed under house arrest at his summer house the day before.

As hundreds of armored vehicles began to roll toward central Moscow, Yeltsin and his closest advisers, including Burbulis, headed for the seat of his government, an imposing marble building known as the White House, where they found crowds of supporters already beginning to gather. The first tanks rumbled up about an hour later.

Around midday, Burbulis says an aide came running into Yeltsin's office to tell him that some of the soldiers had gotten out of their tanks to talk to people in the crowd. Yeltsin's response was immediate: "I'm going out there." He refused to listen to Burbulis' pleas that he could be shot by snipers and marched outside.

With television cameras rolling, Yeltsin shook hands with the tank crew and then hauled himself up onto the tank — a symbol across the world of Soviet power and oppression — and stood to face the crowds. As his alarmed security guards and advisers clambered up around him, Yeltsin read an appeal to "the citizens of Russia" denouncing the coup.

Yeltsin, who died in 2007, wrote in his memoirs that when speaking to the soldiers afterward he could tell by the look in their eyes that they would not open fire.

"I jumped down from the tank and a few minutes later was again back in my office, but I was already a completely different person," he wrote in "Notes of the President," published in 1994.

Yeltsin's improvised performance had an immediate effect. By evening, six tanks had joined his side and the crowds defending the White House continued to grow, reaching tens of thousands by the following day.

The television footage flashing around the world also helped Yeltsin win over foreign leaders, including U.S. President George H.W. Bush, who called him the morning of Aug. 20. Only years later did it become known that Bush had provided Yeltsin with Soviet military communications gathered by U.S. intelligence and arranged for U.S. help in securing the telephone lines in Yeltsin's offices, Harvard University professor Timothy Colton wrote in his 2008 biography "Yeltsin: A Life."

This was crucial as Yeltsin and his team worked the phones in an all-out effort to prevent the coup plotters, who included the Soviet KGB chief and defense minister, from mounting an armed attack.

Burbulis says one little known factor that swayed the outcome was that Yeltsin earlier that year had succeeded in creating a separate Russian KGB whose chief, Gen. Viktor Ivanenko, was loyal to Yeltsin.

"From the first minute we arrived at the White House until the final minute when the coup plotters were taken off to prison, all three days Ivanenko was in my office and did not get up from the chair as he made call after call to his fellow officers, to those very people on whom the coup plotters depended most," Burbulis said.

Others worked to bring military commanders over to Yeltsin's side.

Sergei Filatov, who was with Yeltsin in the White House and later became his Kremlin chief of staff, said he organized teams that were sent to army bases and military academies around Moscow to persuade commanders not to obey orders to storm.

When the coup plotters sat down to plan the storming of the White House they found that too many commanders in the army and KGB refused to carry out their orders.

The plotters were undermined by their own indecision and incompetence, but the main reason the coup failed was the swelling number of people who came to defend the newly elected president of Russia and the freedoms he promised. Any attempt to storm the building would have led to bloodshed.

"We came first of all to defend our government," said Konstantin Truyevtsev, an academic who was among those manning the makeshift barricades around the White House. "For me personally it was for the first time in my country that I had the possibility to choose my government and then these miserable people tried to take it away. So, I went to defend my rights more than anything else."

The coup collapsed on Aug. 22 and Gorbachev returned to Moscow, but power had shifted to Yeltsin. On Dec. 8, he and the leaders of Ukraine and Belarus, with Burbulis co-signing for Russia, dissolved the Soviet Union.

"A revolution is a mixture of spontaneous events and of what you and other people do yourselves," Truyevtsev said. "It is very dramatic."

The mood in the country was one of exhilaration with great hopes for the future. It was not to last.

Just two years later, Yeltsin would send troops to fire on the same White House to subdue a rebellious parliament. His market reforms would impoverish much of the population, while politically connected businessmen would be allowed to grow fabulously rich in exchange for engineering Yeltsin's re-election in 1996 at a time when he was deeply unpopular and ailing.

"My biggest disappointment is that we did not manage to build on what we had achieved at the start," Filatov, who was Kremlin chief of staff from 1993 to 1996, told the AP. "I'm very disappointed with the fact that some parts of the Constitution have almost ceased to work without being officially abolished."

Disillusioned by the flawed democracy of the 1990s, few Russians objected when Vladimir Putin came to power in 2000 and began steadily to erode their political freedoms.

Rallies in Moscow today in defense of democracy draw no more than several hundred people and are usually quickly dispersed by police.