Maxim Shemetov/Reuters
Igor Girkin called Russian President Vladimir Putin a "lowlife" and a "cowardly bum" earlier this week.
CNN  — 

A prominent Russian pro-war blogger who has criticized President Vladimir Putin and his military’s mishaps in Ukraine was arrested on Friday, in a move that suggested the Kremlin’s patience with dissent has grown thinner in the wake of the Wagner mercenary rebellion last month.

Igor Girkin, a former KGB officer who helped Russia seize Crimea and was convicted of mass murder for his role in the downing of Malaysia Airlines Flight 17 in eastern Ukraine, was taken from his home in Moscow by security agents on Friday and charged with “extremist activity,” according to state media and a post on his Telegram account attributed to his wife.

Girkin, who also goes by the nom de guerre Igor Strelkov, is among the best-known of Russia’s “milbloggers,” a group of war correspondents who support the invasion but have grown increasingly critical of the military’s faltering operations in Ukraine. Girkin had in recent months taken his criticisms to another level, lambasting the Russian state and even Putin himself.

He co-founded an ultra-nationalist political group called the Angry Patriots Club this spring, and told Reuters that Russia was “on the cusp of very grave internal political changes of a catastrophic character.”

The day after Wagner’s brief insurrection ended, on June 25, he said that if Putin “is not ready to take the leadership over the creation of war-ready conditions” in Russia, “then he really needs to transfer the powers, but legally, to someone who is capable of such hard work.”

But the final straw for Putin may have come on Tuesday, when Girkin called the president a “lowlife” and a “cowardly bum” in a blistering post on his Telegram channel.

“For 23 years, the country was led by a lowlife who managed to ‘blow dust in the eyes’ of a significant part of the population. Now he is the last island of legitimacy and stability of the state,” the post read. “But the country will not be able to withstand another six years of this cowardly bum in power.”

Miroslava Reginskaya, Girkin’s wife, said in the Telegram statement attributed to her that agents of Russia’s Investigative Committee arrived at their apartment at 11:30 a.m. local time on Friday (4:30 a.m. ET) and took him away “to an unknown direction.”

State news agency Ria Novosti later reported that Girkin had been charged with inciting extremist activity, citing the Meshchansky Court of Moscow.

“Strelkov is charged with Part 2 of Article 280 of the Criminal Code of the Russian Federation (public calls for extremist activity),” the court said, according to Ria. If found guilty, Girkin could be sentenced to up to 5 years in prison.

Another post on Girkin’s Telegram account, attributed to his “associates,” said that his arrest Friday coincided with an attempt to split the Angry Patriots Club over differing opinions about Wagner and its attempted uprising in Russia in June, which posed the most significant challenge to Putin since he took power more than two decades ago.

Girkin “openly and reasonably criticized the actions of government officials, including the president,” the statement from his associates read. They said that confidence in Russia’s “freedom of speech” was being compromised, and that “processes are taking place in our country that indicate the departure of government representatives from basic values.”

Tatiana Stanovaya, a senior fellow at the Carnegie Russia Eurasia Center, said that Girkin had “overstepped all conceivable boundaries a long time ago,” and that his arrest was the result of the Ministry of Defense reasserting control in the wake of the Wagner rebellion.

“This is a direct outcome of [Yevgeny] Prigozhin’s mutiny,” she said on Twitter, referring to the Wagner boss. “The army’s command now wields greater political leverage to quash its opponents in the public sphere. It’s unlikely that there will be massive repressions against ‘angry patriots,’ but the most vehement dissenters may face prosecution, serving as a cautionary tale for others.”

‘Internal confrontation’

Girkin is a former colonel in Russia’s Federal Security Service (FSB) and served as defense minister in the separatist so-called Donetsk People’s Republic (DPR) in eastern Ukraine, territory captured by pro-Russian forces in 2014.

It was during his time in the DPR that he contributed to the shooting down of Malaysia Airlines Flight 17 over eastern Ukraine in 2014, a court in the Netherlands found. All 298 people onboard were killed. The court last year found Girkin guilty of mass murder for his role in the incident and he was sentenced in absentia to life in prison.

According to the court, Girkin participated in the conflicts in Chechnya, Transnistria and Bosnia.

Girkin was remanded in custody until September 18 following his arrest on Friday, after the judge rejected his request to be placed under house arrest due to an apparent heart condition.

The prosecution said Girkin was a flight risk citing his connections to law enforcement agencies, Russian media also reported. In his statement to court, the prominent blogger argued he could not flee abroad, calling the claims “frankly ridiculous.”

His detention comes just three days after Russian state media TASS reported that retired Russian colonel Vladimir Kvachkov, an associate of Girkin’s, was facing criminal prosecution for “discrediting the Russian Armed Forces.”

While TASS did not specify which of Kvachkov’s comments sparked the charges, Kvachkov has also been openly critical of Putin, describing his government is “virtually non-existent” in on-camera remarks at an Angry Patriots event following the Wagner rebellion last month.

Ukraine’s Defense Intelligence later claimed Girkin’s arrest signals there could be growing disputes within the Kremlin.

“The issue is not with Girkin himself, who has never acted as an independent figure before. Neither have many other military correspondents or military bloggers, or members of Girkin’s group. These are not independent figures,” a representative for Ukraine’s defense intelligence, Andriі Yusov, told Ukrainian broadcasters on Friday.

Yusov went on to say it was “paradoxical” that Girkin had been arrested but not Wagner founder Prigozhin.

“Prigozhin was marching on Moscow and shooting down airplanes and helicopters, but Girkin is the one who got detained,” he said. “This is a specific feature of the Putin regime. “

“This all suggests that the members of the Kremlin towers are already coming to an active phase of internal confrontation,” he added, without providing evidence.

CNN’s Yulia Kesaieva, Vasco Cotovio and Katharina Krebs contributed reporting.