Anti-war politician Boris Nadezhdin announced he would end his involvement in opposition politics, saying mounting pressure from the Russian authorities had left him with no choice.

Nadezhdin, 63, was fined on Friday for displaying alleged “extremist” symbols. Before that, he was briefly detained and designated a “foreign agent,” measures that bar him from collecting the signatures needed to appear on the ballot in September’s State Duma elections.

“They are silencing me, forcing me out of politics and making my life increasingly difficult,” Nadezhdin said on Sunday on the Telegram messaging app.

“I no longer have any opportunity to engage in opposition politics legally in Russia. I hope that is only temporary,” he said.

On Friday, a Moscow region judge imposed a fine of 1,000 rubles ($12.76) after finding Nadezhdin guilty of sharing a link to a video that contained an image of the late opposition activist Alexei Navalny, who is on the list of Russia’s terrorists and extremists.