MOSCOW — Russian opposition leader Alexei Navalny, who organized a wave of nationwide protests against government corruption that rattled authorities, was jailed for 15 days on Monday by a Moscow court for resisting police orders.

Navalny was arrested Sunday as he walked to a protest in Moscow and spent the night in jail before appearing in court.

Tens of thousands of anti-corruption protesters took to the streets across Russia on Sunday in the biggest show of defiance since 2011-2012 anti-government protests. President Vladimir Putin’s spokesman on Monday chided opposition organizers for putting people’s lives at risk in the unauthorized protests and defended the actions of Russia’s helmeted riot police, which critics called heavy-handed.

Journalists and well-wishers on Monday packed the courtroom in central Moscow where Navalny was taken. He posted a selfie on Twitter from there, saying: “A time will come when we’ll put them on trial too — and that time it will be fair.”

The 40-year-old Navalny, Russia’s most popular, charismatic opposition leader, has been twice convicted on fraud and embezzlement charges that he has dismissed as politically motivated. Navalny, who is currently serving a suspended sentence, has also recently announced his bid to run in Russia’s 2018 presidential election.