“This is an attempt to silence honest and professional journalism,” Echo of Moscow, Russia’s best-known liberal radio station, said in a statement.
Mr. Smirnov’s jailing came after a night of police violence in central Moscow, where more than a thousand people tried to protest Mr. Navalny’s prison sentence. They were met by an overwhelming show of police force — one Russian outlet reported that more than 8,000 police officers had been deployed — that flooded the grand squares and upmarket side streets near the Kremlin.
“We’ve woken up in a different country, one in which fascists have taken power,” Yevgeny Roizman, the former mayor of the city of Yekaterinburg and a Kremlin critic, wrote on Twitter. “They took over the country earlier, but they stopped hiding it yesterday.”
Police officers in Moscow were filmed swinging batons at pro-Navalny protesters who had their hands up, clubbing a journalist twice on the head and dragging people out of passing cars.
Across Russia, the authorities have made more than 10,000 arrests in the past few weeks, according to OVD-Info, an activist group that tracks detentions at protests. Those jailed or under house arrest include most of Mr. Navalny’s closest allies inside the country and many of his key supporters in the regions.
The Kremlin reiterated on Wednesday that it would not back down.
“There must not be any unsanctioned protest activity,” Mr. Putin’s spokesman, Dmitri S. Peskov, told reporters. “Unsanctioned protests are cause for concern, confirming that the police are justified in their tough, legal actions.”
Still, supporters of Mr. Navalny see momentum on their side, and those allies who have managed to avoid jail called on Russians to be patient and to keep fighting. Mr. Navalny’s prominence is now far greater than it was just a month ago, with extensive coverage even on the state television news. And, even in prison, he may have a unique ability to unite Russia’s disparate opposition — while those allies who are in relative safety outside the country will continue to try to reach Russians online.