A prominent Russian opposition figure was on Friday sentenced to eight and a half years in prison after being convicted on charges stemming from his criticism of the Kremlin’s action in Ukraine.

The sentence handed to one of the few Kremlin critics to have stayed in Russia, Ilya Yashin, offered the latest indication of an intensified crackdown on dissent by Russian authorities. 

“With that hysterical sentence, the authorities want to scare us all but it effectively shows their weakness,” Mr. Yashin said in a statement through his lawyers after the judge handed down the sentence. “Only the weak want to shut everyone’s mouth and eradicate any dissent.”

A jailed Russian politician and Kremlin critic, Alexei Navalny, said via Twitter that Mr. Yashin’s case was “another shameless and lawless verdict by Putin’s court” and said it would “not silence Ilya and should not intimidate the honest people of Russia.”

“This is yet another reason why we need to keep fighting, and I have no doubt we will ultimately win,” Mr. Navalny also tweeted.

Mr. Yashin was charged with spreading false information about the military — a new offense added to the country’s criminal law after President Putin sent troops into Ukraine.

Speaking just before sentencing, Mr. Yashin addressed Mr. Putin directly, urging him to “immediately stop this madness, recognize that the policy on Ukraine was wrong, pull back troops from its territory and switch to a diplomatic settlement of the conflict.”

Asked about the verdict at a briefing, Mr. Putin said he wouldn’t question a court verdict, adding that Mr. Yashin’s lawyers could appeal it.

The charges against Mr. Yashin related to a YouTube livestream video in which he talked about Ukrainians being killed in the Kyiv suburb of Bucha. He rejects the charges as politically motivated.

During the trial at Moscow’s Meshchansky District Court, Mr. Yashin argued that his case has been fabricated and “has all the markings of illegal political persecution.” He noted that in the video he cited Russian official sources along with Ukrainian statements to give his audience an objective view.

In his final remarks, Mr. Yashin emphasized that he considers it his duty to tell the truth, saying: “I will not renounce the truth behind bars.”

“When the hostilities began, I didn’t hesitate for a second,” Mr. Yashin said. “I felt I should remain in Russia, loudly tell the truth and try to do all what I could to end the bloodshed. It’s better to sit behind bars for a decade and remain an honest person than silently feel shame for the blood spilled by your government.”

Human Rights Watch denounced Mr. Yashin’s sentencing as part of “continued efforts to dismantle and decapitate Russia’s peaceful political opposition” and demanded his immediate release.

“The verdict against Yashin is a travesty of justice and an act of cowardice, directed by a Kremlin that feels threatened by vocal and visible critics like him,” the deputy Europe and Central Asia director at Human Rights Watch, Rachel Denber, said.

Amnesty International’s Russia director, Natalia Zviagina, noted that “heavy fines, imprisonment, loss of livelihood, harassment, and physical attacks are all being used to silence those who protest or speak out against the war of aggression against Ukraine.” She added: “In today’s Russia, telling the truth about human rights violations has literally been made a crime.”

Days after Mr. Putin sent troops into Ukraine on February 24, Russia’s Kremlin-controlled parliament approved legislation that outlawed alleged disparaging of the Russian military or the spread of “false information” about the country’s military operation in Ukraine.

Dozens of Russian independent media outlets were banned as a result and others announced that they would halt any reporting related to Ukraine.

Authorities have also continued to label independent journalists and media outlets as “foreign agents,” a designation that carries negative connotations and implies additional government scrutiny.

The Russian justice ministry on Friday designated the Bell online publication and a few individuals as “foreign agents.”

A lawyer for Mr. Yashin,  Vadim Prokhorov, told the Moscow Times that with respect to the harsh sentencing, “This hasn’t happened for a long time, since the Brezhnev era,” adding that “we will use all legal means to appeal the verdict. I am sure that over time the sentence will be quashed, and Yashin will be cleared.”