Russia has detained a American citizen in Moscow on accusations of spying, according to Russian state media.

Russian Federal Security Service (FSB) officials issued a statement on Monday saying U.S. citizen Paul Whelan had been detained on December 28 “while carrying out an act of espionage,” and that they have opened a criminal probe.

They provided no further details, but Russia’s state-run TASS news agency said that Whelan faces up to 20 years in prison if convicted.

There was no immediate reaction from U.S. officials.

The arrest coincides with several spy scandals that have exacerbated tensions between Russia and the West, including the poisoning of former double agent Sergei Skripal and his daughter in Britain, along with the recent U.S. conviction of Russian citizen Maria Butina for acting as an illegal foreign agent.

News of Whelan’s detention came less than 24 hours a after Russian President Vladimir Putin issued a New Year’s greeting to President Donald Trump in which he said Moscow is amenable to a continuing dialogue with Washington on a range of topics.

In 2016, Izvestia, a Kremlin-aligned news outlet, reported that there were 13 U.S. citizens in Russian jails at the time. The Kremlin has not since published any details on other Americans currently in Russian detention.