As tens of thousands protest corruption throughout Russia on Monday, prominent opposition figure Alexei Navalny is not among them. Navalny was reportedly arrested 30 minutes before things were set to kick off in Moscow, with wife Yulia tweeting, "Alexei has been arrested in the entrance to our block of flats," but "our plans haven't changed," per the BBC. That will make for one fewer protester on a day when NBC News suggests numbers count: The "scale and geographical reach" will indicate whether Navalny was able to successfully grow protests held in March that saw more than 1,000 people arrested. Those protests—spurred by Navalny's charges that Prime Minister Dmitry Medvedev had enriched himself with $1 billion worth of mansions, yachts, and vineyards, reports the Washington Post—were the largest in roughly five years.
NBC News notes one favorable condition as far as turnout goes: Monday is Russia Day, a public holiday. The Post sees the protests as a sort of bellwether for Navalny, who wants to take the presidency from Vladimir Putin in 2018 (though Navalny has technically been disqualified as a candidate). As for why Navalny was arrested, Moscow's general prosecutor indicated it was over his "illegal" last-minute call to change the protest location in that city from the approved spot, where plans to erect a stage were apparently scuttled, to Tverskaya Street near the Kremlin. After the venue-change announcement, the AP reports Moscow police warned "any provocative actions from the protesters' side will be considered a threat to public order and will be immediately suppressed." (Navalny was partially blinded by toxic green dye in April.)