People visit Khreshchatyk Street where destroyed Russian armoured military vehicles are on display on Ukraine s Independence Day in Kyiv, on August 24, 2023, amid the Russian invasion of Ukraine. AFP
The Federal Security Service (FSB) said in a statement it had "suppressed the illegal activities of Robert Robertovich Shonov", accusing him of being an informant for the US embassy in Moscow.
The announcement is the latest in a series of diplomatic spats building pressure on strained ties between Moscow and Washington, particularly over the conflict in Ukraine.
The FSB said Shonov had begun handing information to US diplomats in September last year about the conflict and mobilisation, an unpopular move in Russia that saw an exodus of military-aged men.
It added that Shonov had been tasked with gauging protest sentiment in Russia's regions ahead of presidential elections scheduled for next year.
The FSB said that Shonov had reported to two diplomats in the political department in the US embassy in Moscow, Jeffrey Silin and David Bernstein, and that it planned to question the men.
Diplomatic tensions between Russia and Western countries, particularly the United States, have been deteriorating for years and both sides have ordered the other to cut staff numbers at diplomatic facilities, hampering their functions.