MOSCOW — Russian President Vladimir Putin refuses to say his name, in a show of disdain. But there is no doubt that Russian opposition leader Alexei Navalny weighs heavily on minds in the Kremlin.

Here is what you need to know about the showdowns between Putin and Navalny, who leads a network of activists, political allies and social media coordinators.

Where is Navalny now?

In jail. The 44-year-old Navalny was taken into custody after flying home on Jan. 17 from Germany, where he was treated for a near-fatal nerve agent poisoning in August that occurred while he was on a trip in Siberia. He claims Putin ordered the poisoning. The Kremlin denies any role but refuses to open a criminal investigation into the episode.

Navalny, however, has three criminal cases hanging over him — all of them politically motivated, he says. Any one of them could land him in prison for years.

So what worries Putin?

The Kremlin most fears a "color revolution" — massive and uncontrollable protests such as Ukraine's Orange Revolution, which occurred from late 2004 to early 2005, or Georgia's Rose Revolution in 2003. So Putin's security forces slap down any major city protests fast and hard, using mass arrests, Internet blockages, long prison sentences and constant harassment of political opponents.

What's next for Navalny's supporters?

Navalny has called for street protests. Tens of thousands of supporters took to the streets across Russia on Jan. 23 and more demonstrations are expected. But there are no realistic chances of driving Putin from power, at least not in the short term. Even the more modest aim of forcing authorities to release Navalny seems a long shot. He has been declared an enemy of the state. At the same time, Putin’s security forces have expanded crackdowns against other opposition figures, journalists and activists.

Does Navalny have other political tools?

Definitely. In fact, much of Navalny’s strength lies in the ability to harness social media to keep pressure on Putin and his allies, exposing alleged corruption and indulgences.

On Jan. 19, Navalny’s group released a bombshell video on YouTube accusing Putin of colossal corruption. It claimed Putin secretly built a palatial compound on Russia’s Black Sea coast and fathered a daughter during an affair. The Kremlin spokesman dismissed the video as “a con” and “pure nonsense.” But it was viewed more than 25 million times in less than 24 hours.

In 2017, Navalny’s YouTube channel posted video showing the country mansion of then-Prime Minister Dmitry Medvedev — complete with its own luxury duck coop. Navalny organized anti-corruption rallies in 95 cities. The protest symbol of the day was a rubber duck. Navalny and more than 1,000 others were arrested, human rights observers said. Mass anti-corruption protests continued through the year.

How long has Navalny been battling Putin?

For more than a decade. Navalny began as a crusader against corruption. Then protests erupted in December 2011 after Putin said he would run for a third presidential term. The opposition also alleged fraud in parliamentary elections won by Putin’s party, United Russia. Campaigning for the presidency, Putin claimed dark foreign forces were trying to ignite a “color revolution.”

In May 2012, a “march of millions” led to 37 people being charged with rioting and assaulting police. Witnesses, however, saw no such incidents. Among the many protest leaders were Navalny and Boris Nemstov, who was killed by gunmen in 2015 near Red Square in Moscow.

What happened next?

A court jailed Navalny for five years in July 2013 on embezzlement charges. Navalny said the charges were political retribution. Protesters immediately flooded the streets near the Kremlin after the sentencing. Navalny tweeted a farewell: “OK. Don’t get bored here without me. And most importantly, don’t hang about. The frog won’t jump off the oil pipes itself.” He meant Putin, squatting atop an economy built on oil.

Mikhail Gorbachev, the last Soviet leader, said the sentence proved the Russian judiciary was not independent, and even some politicians close to Putin expressed dismay. The pressure seemed to work. Navalny was ultimately given a suspended sentence.

Did Navalny try to run against Putin?

Yes, in 2018. But he was barred from the ballot by election authorities. Protests over the decision erupted in 118 cities. Navalny mounted mass protests in 90 cities after Putin won. The slogan: “He’s not our czar!” At least 1,612 people were detained.

Later that year, yet more protests erupted over Putin’s move to raise the age for pension eligibility.

And in July 2019, thousands of people demonstrated in Moscow after dozens of independent candidates were barred from elections. Navalny sought to hold a second rally, but authorities swooped in. He was jailed for 30 days. The protests continued into August. Nine protesters, charged with rioting or assaulting police, received prison sentences of up to 3½ years.

What about in other parts of Russia?

Russia’s Far East has been an unexpected hot spot for anti-government protests.

In July 2020, authorities arrested a popular local governor in Khabarovsk on murder charges, which the governor denied. The Kremlin was taken aback when thousands of protesters took to the streets. The outpouring — about 3,800 miles east of Moscow — tapped into local discontent, uniting disparate political forces and lasting months. The Kremlin’s appointment of a new governor intensified the public’s anger.

For Putin, it was a wake-up call on the disquiet in Russia’s distant regions. At the same time, Belarusian leader Alexander Lukashenko faced mass protests after a disputed election. He clung on — just — using brute force, including torture, as the Kremlin looked on with alarm.