U.S. Secretary of State Mike Pompeo took to Twitter late Sunday to criticize Russia’s decision to arrest Alexei Navalny, the opposition leader who just returned to Moscow after recovering from nerve agent poisoning that he blames on the Kremlin.
"Deeply troubled by Russia's decision to arrest Aleksey Navalny," Pompeo tweeted. "Confident political leaders do not fear competing voices, nor see the need to commit violence against or wrongfully detain, political opponents."
Jake Sullivan, President-elect Joe Biden’s national security adviser, also took to Twitter to call for Navalny’s immediate release.
"The Kremlin’s attacks on Mr. Navalny are not just a violation of human rights, but an affront to the Russian people who want their voices heard," Sullivan tweeted.
Navalny’s detention at passport control in Moscow’s Sheremetyevo airport was widely expected because Russia’s prisons service said he had violated parole terms from a suspended sentence on a 2014 embezzlement conviction.
Navalny traveled from Berlin to Moscow after recovering in Germany from his poisoning in August. Confusion surrounded his arrival in Russia -- his plane was scheduled to land at Moscow's Vnukovo Airport, where supporters and media were waiting.
The 44-year-old, who is President Vladimir Putin’s most prominent political foe, brushed off concerns about arrest as he boarded the plane in Berlin.
"It’s impossible. I’m an innocent man," he said.
Fox News' James Rogers and the Associated Press contributed to this report