MOSCOW (AP) — Russian opposition leader Alexei Navalny was released today after spending a month in jail for calling for an unsanctioned protest.

Navalny, along with several opposition activists, has led a protest movement earlier this summer against Russian election authorities’ decision to bar nearly two dozen independent candidates from running for the Moscow city legislature in the Sept. 8 election. One of these rallies was the largest anti-government protest that Moscow had seen in eight years.

Speaking to reporters outside the detention facility in Moscow, Navalny vowed to keep fighting against Russian President Vladimir Putin’s government despite the increasing pressure.

“I have no doubts that despite these acts of intimidation and terrorizing that are happening now, like arrests of innocent people, this wave (of protests) will grow,” he said, adding that the government’s heavy-handed tactics shows that popular support for the Kremlin is waning. “They feel it, and they’re scared of it.”