Moscow - It took Stanislav Petrov 23 minutes to prevent mutually assured nuclear destruction of the United States and the USSR, and for years only a handful of Communist leaders knew about the apocalypse he single-handedly averted 34 years ago today.

It was September 28, 1983, when Lieutenant Colonel Petrov - a lanky, 44-year-old military analyst with the Soviet Air Defence Forces - started his night shift. He was chief duty officer at a military command centre 100km west of Moscow.

Dubbed by officers and locals "The Champignon", the centre looked like a gigantic concrete mushroom encircled by barbed wire and hundreds of armed soldiers. It was connected to four spy satellites that monitored the continental United States and adjacent oceans.

OPINION: Is Russia a real threat to the West?

The centre was equipped with a supercomputer and gigantic electronic maps of the USSR and the US that showed the site of a missile launch and its destination. It was designed to detect ballistic missile launches from nine US bases, compute their trajectories, and report the findings to Soviet leaders and top military brass.

But the night shifts were not exactly a dream job for Petrov and about 100 people under his command.

"It was so boring it sometimes made me feel sick," Petrov told this reporter in June 2016.

Boring, that is, until he heard a deafening siren and saw the word "START" on the map - next to a west coast military base that launched a Minuteman intercontinental ballistic missile. Flying over the Arctic at 7.8 kilometres per second - almost enough to leave Earth's gravity - the ICBM could reach Moscow within 40 minutes.

The computer confirmed the attack's veracity as the "highest" threat level, Petrov recalled. The launch site looked like a pulsating human heart.

Tense prelude

The year 1983 was the peak of the Cold War and the most polarising, Manichean confrontation in human history.

The Soviet Union and the US knew any attack would trigger a nearly automatic squall of missile launches from the other side.

MAD, or mutually assured destruction, would kill hundreds of millions and cause a nuclear winter that would most likely ruin life on Earth.

Then US President Ronald Reagan - whom Soviet media branded a "war monger" - ordered the US military to probe Soviet air defences with what the Pentagon dubbed "psychological warfare operations".

"Sometimes we would send bombers over the North Pole, and their radars would click on," General Jack Chain, a former Strategic Air Command commander, was quoted as saying in A Cold War Conundrum: The 1983 Soviet War Scare, a book by Benjamin B Fischer.

"Other times fighter-bombers would probe their Asian or European periphery."

READ MORE: Russia - A resurgent superpower?

Four weeks before Petrov's graveyard shift, the Soviets shot down a South Korean plane with 269 passengers aboard, including a US congressman, that briefly entered the USSR's airspace - drawing international condemnation and economic sanctions.

Four years earlier, red Moscow invaded Afghanistan and thousands of armed fighters - often trained and armed by the US - flocked to fight the Soviet "infidels".

The Muslim world was indignant, and USSR's Middle East allies were under attack. Reagan bombed Soviet-friendly Libya and intervened in the Lebanese civil war against pro-Moscow Syrian President Hafez al-Assad.

Reagan announced the development of Star Wars, an astronomically expensive, space-based defence installation to shoot down Soviet ballistic missiles in midair.

He also convinced Saudi Arabia to boost oil production; the plunging prices hobbled the ineffective Soviet economy that depended on hydrocarbon exports - and pushed it into a decade of stagnation it would never recover from.

Its heaviest burden was the Red Army, which consumed one quarter of Soviet GDP. Communist leader Yuri Andropov, a former KGB chairman and Russian President Vladimir Putin's role model, was convinced that the US was readying for an all-out nuclear war, and the future of the Communist utopia was at stake.

"The threat of nuclear war overhanging mankind causes one to reappraise the principal goals of the activities of the entire Communist movement," Andropov said in June 1983.

Soviet and US leaders were paranoid. The Doomsday Clock, a symbolic indicator of the global nuclear war maintained by US atomic scientists, was set at four minutes to midnight.

Armageddon?

It was 15 minutes after midnight when the sirens at the Champignon on that September night went on.

"One, two, five rockets. When there is more than two, the computer called it a nuclear missile attack," Petrov recalled.

He had to confirm the attack on the phone and push the red panic button that would trigger alarms throughout Soviet missile installations.

Tens of thousands of military officers and soldiers would have to get ready and target their missiles and wait for a command from Andropov.

But the satellite signal did not detect "tails", or visible traces of flying missiles. The scope of the attack also seemed illogical - the US would not start a nuclear annihilation of the USSR with just five missiles, Petrov thought.

Meanwhile, Soviet ground-based radars didn't detect any signals - and he decided the system had malfunctioned.

"I understood the signal was wrong and yelled, 'False alarm! False alarm!'" he said. "I made a decision not to believe the computer."

Oblivion

"Almost immediately, we understood that the reason was a computer glitch," retired Colonel General Yuri Votintsev, head of the Soviet Air and Space Defence at the time, was quoted as saying by the Rossiiskaya Gazeta daily's report released in September.

"But it was not just that. As a result of an investigation, we discovered an entire bunch of defects in the early warning system."

The investigation found the Soviet satellite mistook rare reflections of sunlight from clouds for the flashes generated by missile launches.

Votintsev praised Petrov - but that was it, because by awarding him his superiors would have to admit the lethal ineffectiveness of the exorbitantly expensive early warning system.

READ MORE: In praise of the AK-47 - Russia unveils statue of Mikhail Kalashnikov

Petrov retired from the military in 1984 and worked at a research facility that remodelled the early warning system. It was retrofitted by 1985 - when new Soviet leader Mikhail Gorbachev started the perestroika reforms and peace talks with Reagan's White House.

Petrov's fateful decision remained unknown to the public until a 1991 newspaper report based on Votintsev's memoirs.

Post-Soviet Russia never acknowledged him with awards, and some military analysts doubted his role in preventing the nuclear apocalypse.

"Nothing would have happened, and he did not have to pass any [information], he would not have been able to signal anything because the warning signal reached all screens, but everyone understands very well that that such signals occur occasionally," retired General Pavel Zolotaryov said in televised remarks in 2013.

Recognition from the West

In 2006, Petrov received a special award from the Association of World Citizens, an anti-war group, at the United Nations headquarters in New York.

In 2014, Danish filmmaker Peter Anthony released The Man Who Saved the World, an award-winning documentary about Petrov.

Petrov lived in a dilapidated apartment in the Moscow suburb of Fryazino. In the mid-1990s, he had to grow potatoes on a patch of land to supplement his meagre pension, he said.

His son and daughter moved out in the 1990s, and his wife died of cancer in 1997.

"I live here quietly, all alone," the frail, bespectacled and nearly blind septuagenarian said clutching the crystal award, a small hand that holds a globe.

He died of pneumonia on May 17, aged 77, and his demise was only reported in mid-September.