The most prominent opponent of Vladimir Putin in Russia, Alexei Navalny, has called on people around the world to stage daily protests against the Kremlin’s brutal invasion of Ukraine. In a string of tweets sent from his prison cell, the Russian opposition leader called Putin “our obviously insane czar” and sent out a call to action. “We cannot wait any longer,” Navalny wrote. “Wherever you are, in Russia, Belarus or on the other side of the planet, go to the main square of your city every weekday and at 2 pm on weekends and holidays. If you are abroad, come to the Russian embassy. If you can organise a demonstration, do so on the weekend.” Navalny was imprisoned last year after he returned to Russia from Germany following his recovery from a nerve-agent attack by FSB agents.