The U.S. State Department says Russia has expelled Bart Gorman, the deputy chief of mission at the U.S. Embassy in Moscow.
A spokesman for the embassy confirmed the expulsion on February 17 but gave no details on why the move was taken.
"Russia’s action against our DCM was unprovoked and we consider this an escalatory step and are considering our response," a spokesperson for the U.S. State Department said.
The Russian state RIA Novosti news agency said that Gorman was second in command at the U.S. Embassy in Moscow and had an open visa. He has spent less than three years in Moscow, the agency said.
The move comes amid heightened tensions between Washington and Moscow over Russia's buildup of troops in border areas with Ukraine. U.S. officials, along with some other Western officials, have said that a Russian invasion of Ukraine could be imminent.
Moscow has denied it has any plans to invade Ukraine.