Chanting slogans against President Vladimir Putin, thousands of people took to the streets on Sunday across Russia’s vast expanse to demand the release of jailed opposition leader Alexei Navalny, keeping up the nationwide protests that have rattled the Kremlin. On Sunday, police detained More than 4,000 people at protests held in cities across Russia’s 11 time zones, according to OVD-Info, a group that monitors political arrests.

Russian authorities mounted a massive effort to stem the tide of demonstrations after tens of thousands rallied across the country last weekend in the largest, most widespread show of discontent that Russia has seen in years. Yet despite threats of jail terms, warnings to social media groups and tight police cordons, the protests again engulfed many cities on Sunday.