By PATRICK REEVELL, ABC News

(MOSCOW) — A Russian court ordered opposition leader Alexey Navalny be sent to a prison camp for two years and eight months, imprisoning President Vladimir Putin’s fiercest critic despite an international outcry and protests in Russia that have roiled the country.

As the verdict was read out, Navalny, who was poisoned with a nerve agent last summer, smiled and shrugged inside a glass cage in court.

Tuesday’s decision by a judge at Moscow’s city court was to uphold a request by Russia’s federal penitentiary service to change an old suspended jail sentence into a real prison term on the grounds Navalny had allegedly violated the terms of his parole.

That sentence, though, was from an embezzlement trial in 2014 widely criticized as politically motivated and that the European Court of Human Rights found was unjust and part of a pattern of political persecution of Navalny. The suspended sentence was for three and a half years, but the judge reduced it to take into account a year Navalny already spent under house arrest for the same conviction.

In a fiery closing speech before the decision, Navalny castigated the hearing, calling it a show trial.

“They want to jail me for a case in which I was found innocent,” Navalny said, pointing to the European Court ruling. He said he was there because Putin had hoped to deter him from returning to Russia after the poisoning.

“Someone really wanted that I not take a step onto the territory of Russia. And we know why. The reason is the fear of one person sitting in a bunker,” Navalny said, referring to Putin. “And he is afraid because I have caused him a mortal insult. I caused him a mortal insult by surviving.”

The decision to send Navalny to a distant prison camp was widely viewed as an attempt to neutralize him as a political threat to the Kremlin.

It prompted immediate criticism from European countries and the United States, with Secretary of State Anthony Blinken issuing a statement calling for Navalny’s immediate release along with that of people detained at recent protests.

Blink said the proceedings against Navalny “are​ a continuation of efforts to violate Mr. Navalny’s rights and suppress political pluralism.” He said the U.S. would work with its allies to hold Russia accountable for failing to uphold the rights of its citizens.

Immediately following the ruling, Navalny’s supporters in Moscow called for people to protest on the city’s Manezh Square in front of the walls of the Kremlin.

The decision to imprison Navalny marked another decisive moment in the showdown between Navalny and the Kremlin. Navalny returned to Russia just over two weeks ago for the first time since his poisoning and was arrested immediately at the airport in Moscow.

On Sunday, for the second weekend running, thousands of people joined protests across Russia in support of Navalny, despite a huge security clamp-down. Heavy deployments of riot police dispersed crowds in cities across Russia, while authorities shut down Moscow’s center. Over 5,400 people were detained, the most during protests under Putin.

During the trial Tuesday, police sealed off several streets around the court, ringing it with lines of helmeted riot officers, who swiftly detained anyone they deemed a protester. Over 200 people were detained near the court early in the day.

Through the court hearing, Navalny laughed and smiled at his wife, Yulia, who was in the courtroom.

Prosecutors argued that Navalny had failed to check in twice a month with prison authorities as required by the terms of his suspended sentence for much of last year. This time included when he was hospitalized in Germany after being poisoned.

Navalny, who was airlifted to Berlin for treatment after being exposed to a Novichok nerve agent in Siberia and spent three weeks in a coma, asked the prison representative in court how he could have checked in while he was in a coma.

Navalny has blamed his poisoning on Putin, accusing members of Russia’s domestic intelligence agency the Federal Security Service of putting the nerve agent into his underwear.

“His main grievance against me is that he will go down in history as a poisoner,” Navalny said of Putin. “You’ve got Alexander the Liberator and Yaroslav the Wise. And now we’ll have Vladimir the Underwear Poisoner.”

Navalny, 44, has been jailed briefly many times before for his activism, but has never previously been sent for lengthy period of a prison camp, something many observers believe the Kremlin has previously deemed not worth the potential political fallout.

In 2014, during the fraud trial which produced the suspended sentence, Navalny was originally sentenced to prison time, but after an outcry and small protests in Moscow, law enforcement officials abruptly backtracked and released him. In that trial, Navalny was found guilty of embezzling money from the Russian branch of the cosmetics brand Yves Rocher, one of a series of legal cases brought by authorities over the years widely criticized by international rights groups as politically motivated.

The decision to press ahead with jailing Navalny this time, despite a far greater outcry in Russia and abroad and despite the two weeks of protests, suggests the Kremlin’s calculus has now changed and that it now views it as too dangerous to allow Navalny to remain free.

The Kremlin has denied any role in Navalny’s poisoning and on Tuesday as the hearing began its spokesman Dmitry Peskov told reporters Putin was not following the trial.

Speaking before the verdict, Peskov said he hoped the European Union would not do “such nonsense as the linking of the future of Russia-EU relations to the case of this inmate of a detention facility.”

A former lawyer, Navalny has built a grassroots following mostly through investigations — posted as online viral videos — exposing alleged corruption among powerful Russians close to the Kremlin.

Since returning to Russia, his team released a new film alleging to unveil the staggering luxury of palace built secretly by Putin on the Black Sea. The film has since been watched over 100 million times on YouTube and forced a rare comment from Putin denying he owns the palace. Pro-Kremlin media have since been allowed to tour the palace and a childhood friend and former judo sparring partner of Putin, the oligarch Arkady Rotenberg, over the weekend appeared in a report claiming he owned the building and intended to turn it into an apartment hotel.

In his closing speech, Navalny told the judge he hoped people would not be scared by his imprisonment.

“It’s not difficult to jail me,” he said. “It’s a demonstration of weakness. It’s impossible to jail millions and hundreds of thousands of people. And when people realize that — and that moment will come — then all this will fall apart.”

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