A Moscow court has sentenced Alexei Navalny to two years and eight months in a prison colony in a landmark decision for Vladimir Putin’s crackdown on the country’s leading opposition figure. Navalny, who has accused the Russian president and his allies of stealing billions, was jailed for violating parole from a 2014 sentence for embezzlement in a case he has said was politically motivated. The court’s decision makes Navalny the most prominent political prisoner in Russia and may be the most important verdict against a foe of Putin’s since the 2005 jailing of the oligarch Mikhail Khodorkovsky. Ahead of the verdict, Navalny looked across the court room to his wife Yulia, and traced a heart on the glass around the dock. After a judge read the verdict, subtracting the 10 months he had spent under house arrest from his original three-and-a-half-year sentence, Yulia took off her mask, smiled, waved, and then shrugged. “Don’t be sad! Everything’s going to be alright!” Navalny yelled to her. She declined to comment as she walked out of the courtroom, looking straight ahead. Outside the courthouse, she stood next to Navalny’s two lawyers, Olga Mikhailova and Vladimir Kobzev. They said they planned to appeal to the European Court on Human Rights. “You saw what happened in there,” Mikhailova said. “It was a horror, like always.” After the verdict, several hundred Navalny supporters marched in central Moscow. Videos by local media or shared on social media showed police in body armour hitting protestors with staves. More than 1,000 people were arrested across Russia in the course of the day, according to the independent monitoring group OVD-info. The Kremlin’s decision to send Navalny to prison came despite the threat of further street protests and international condemnation from the US government and other foreign leaders. Diplomats from more than half a dozen western countries attended the court. In a fiery speech from a Moscow city courtroom decorated with portraits of Cicero and Montesquieu ahead of the sentencing, Navalny had accused Putin of ordering his assassination with the poison novichok and said that the Russian leader’s “only method is killing people”. The US secretary of state, Anthony Blinken, said Washington was “deeply concerned” and reiterated calls for Navalny’s unconditional and immediate release, saying it would coordinate with allies to hold Russia accountable. Boris Johnson described the ruling as “pure cowardice,” which failed to meet “the most basic standards of justice”. “Alexey Navalny must be released immediately,” he wrote. The German foreign minister, Heiko Maas, described it as a “bitter blow” to the rule of law in Russia. The sentencing has shown the exhaustion of Russia’s leaders with Navalny, who even from jail released a detailed investigation into a £1bn Black Sea palace allegedly built for Putin’s use. He was arrested upon returning to Russia last month after surviving a suspected FSB assassination attempt in August 2020 with a novichok poison similar to that used in Salisbury in 2018. Russian prison officials had said while Navalny recovered in Germany that they would seek to jail him for violating parole in the 2014 case in an apparent attempt to keep the Kremlin critic in exile, but he flew back all the same. “Someone did not want me to take a single step on my country’s territory as a free man. And we know who and we know why – the hatred and fear of one man, living in a bunker, whom I offended by surviving when he tried to have me killed,” he said of Putin. “His only method is killing people. However much he pretends to be a great geopolitician, he’ll go into history as a poisoner.” “We all remember Alexander the Liberator and Yaroslav the Wise. Now we’ll have Vladimir the Poisoner of Underpants.” “This isn’t a political rally,” the judge interrupted him at one point. “Let’s not do politics here.” The 16-minute speech may be one of the opposition leader’s last public orations in the coming years. Investigators are preparing to bring new charges against Navalny on fraud and other charges that could carry a sentence of another decade in a penal colony if they are brought to trial. In his remarks, Navalny called on his supporters not to fear the government, saying: “You can’t imprison the whole country.” More than 5,000 people were detained in nationwide protests this weekend and senior Navalny aides have been swept up in government raids. “Locking me up isn’t difficult,” Navalny told the court. “This is happening to intimidate large numbers of people. They’re imprisoning one person to frighten millions.” He called the court case a “performance”. “This is what happens when lawlessness and tyranny become the essence of a political system, and it’s horrifying,” he said. For years, the government had harassed Navalny, holding him under house arrest, jailing his aides and imprisoning his brother for three-and-a-half years in 2014. But until Tuesday, it had stopped short of giving him a long prison sentence, apparently fearing a backlash. In 2013, a judge abruptly set Navalny free on parole one day after thousands protested against his five-year prison sentence on the streets outside the Kremlin. The sudden about-face confirmed what many in the opposition believed: that important court decisions are made in the Kremlin. The government’s mood apparently changed following the failed assassination attempt and a deeply embarrassing investigation by Bellingcat, which exposed the attack as the work of an FSB hit squad who had shadowed Navalny around Russia for years. In a flourish, Navalny managed to elicit a confession from a member of the FSB, the Russian intelligence service that Putin formerly headed. Diplomats at the hearing were chased by state television journalists peppering them with questions about whether they were extending Navalny political support. Navalny’s allies have also called for new sanctions against some of Putin’s closest allies and the officials involved in his case. Maria Zakharova, a spokeswoman for the Russian foreign ministry, called the western diplomats’ presence “meddling”. “It exposes the mean and illegal role of the collective west in attempts to restrain Russia,” she said. “Or is it an attempt to put psychological pressure on the judge?”