It seemed likely to be a short-lived appointment. Putin's predecessor had lasted only a few months in the job, and Yeltsin had seen three other prime ministers come and go following the financial crash of August 1998.

At the time, Putin possessed none of the aura of a world leader. Before joining the Yeltsin administration, he had a largely behind-the-scenes career as an adviser to St. Petersburg's mayor, Anatoly Sobchak. He then moved to Moscow to work for the Presidential Property Management Department, an unlikely springboard to national office.

But within less than six months of making him prime minister, Yeltsin unexpectedly handed Putin the presidency on New Year's Eve, 1999. That historic surprise set in motion Putin's extraordinary rise to become the undisputed leader of Russia.

The numbers speak for themselves. In August 1999, when he became prime minister, independent pollster Levada Center put Putin's approval rating at 31%. By January of 2000, after taking over as president, it was 84%. According to Levada, it has never dipped below 60% since then.

What explained Putin's surge in popularity over those crucial early months?

One factor was clear: Putin's muscular response to domestic terrorism. In September of 1999, a string of mysterious apartment bombings killed hundreds of people in several cities around Russia and paralyzed the country with fear.

It was a 9/11 moment for Russia. And, much like President George W. Bush, who would promise retribution against al Qaeda in his bullhorn speech to emergency rescuers at Ground Zero in New York after September 11, 2001, Putin delivered the kind of tough talk that many Russians wanted to hear.

"We will pursue terrorists everywhere," Putin vowed, as Russian forces bombed the capital of the breakaway republic of Chechnya . "If they are the airport, in the airport. That means -- pardon my language -- that if they're on the toilet, we will waste them out in the outhouse."

Russian investigators concluded the attacks were perpetrated by Islamic extremists. But Putin's opponents -- most famously, exiled tycoon Boris Berezovsky and former Russian spy Alexander Litvinenko -- went on to promote the dark conspiracy theory that Russian security services had a hand in staging the apartment bombings as a provocation aimed to force military action in Chechnya.

Regardless of the perpetrator, the bombings represented a turning point in Putin's career: It brought the nation behind him and built popular support for his rule.

Equally important, it allowed the Kremlin's formidable spin machine to mold Putin's image as a powerful leader. In 1999, Russians were collectively traumatized by collapse of the USSR and the transition to a market economy. Putin's decisiveness was presented as a contrast to Yeltsin's erratic rule.

Not long after becoming acting president, Putin flew to Grozny, the capital of Chechnya, in an Su-27 jet. A Kremlin news release at the time noted that he had piloted the plane himself during part of the flight.

The myth-making machine would work tirelessly over the next two decades to refine that image of Putin as a man of action.

The 1999 military campaign in Chechnya also created the template for Putin's way of war. Russian forces leveled the rebel capital of Grozny. Images of the ruined city would look strikingly similar to besieged Syrian cities such as Aleppo, which would come under intense bombardment by Russian warplanes after Putin launched a military intervention there 2015

Putin's war on terrorism -- at least initially -- found common cause with the West. After the 9/11 attacks, Putin was the first world leader to call Bush. The Russian government acquiesced to a US military presence in Central Asia to support of the invasion of Afghanistan ; it subsequently allowed US troops and equipment heading for Afghanistan to cross Russian airspace, something unthinkable during the Cold War.

The Kremlin leader, however, was wary of US intentions. He criticized the expansion of the NATO alliance, opposed US plans to development ballistic-missile defense, and -- in what would come to define Russia's relations with the world -- seized Crimea in 2014.

The annexation of Crimea came at a cost: Russia was hit with economic sanctions by the US and its allies. Those sanctions hit the pocketbooks of ordinary Russians, but it did little to diminish Putin's prestige. Putin also stuck to a policy of strict fiscal discipline: Earlier this summer, the Russian Central Bank confirmed that foreign-currency reserves had topped $500 billion.

In contrast to 1999, the Kremlin's grip on Russian media is tighter today. A steady crackdown on press freedoms over Putin's tenure means there is very limited critical coverage -- at least domestically -- of his policies.

Russian state media have done little to mark Putin's two decades in power. But after 20 years in office, some cracks are beginning to show in his façade as leader. While Putin still enjoys high ratings, they are now nowhere near the level seen after Russia's annexation of the Black Sea peninsula of Crimea from Ukraine in 2014 provoked a wave of patriotic sentiment.

In recent weeks, a new wave of street demonstrations over municipal elections has presented a new challenge to the Kremlin. While the protests pose no direct threat to Putin's monopoly on power, Russia's small and fragmented opposition has used their marches to express discontent with what they see as a president who has stayed too long in office, as well as with a ruling elite that seems to have run out of fresh ideas.

Foremost on the minds of Russia's political class is the fact that no clear successor has emerged for Putin. By law, Putin must step aside after his next term ends in 2024. But many observers speculate that Putin may engineer a way to keep himself in office, much like President Xi Jinping of China , or like the former president of Kazakhstan, Nursultan Nazarbayev, who formally stepped aside but who still holds formal levers of power.

In unsanctioned street-art festival in the city of Yekaterinburg earlier this year, a street artist named Filipp Kozlov -- who goes by the handle Philippenzo -- painted a grainy graffiti image of ballerinas dancing Swan Lake, an allusion to the ballet that was famously broadcast during the coup against Soviet leader Mikhail Gorbachev in August 1991.

"For 20 long years, we've been waiting with hope for the ballet," the subversive caption read, in a clear reference to Putin's two decades in power.