A US Army soldier stationed in South Korea has been detained in Russia, the US military says.
The Russian Ministry of Foreign Affairs said the charges were not related to "politics or espionage" but to a "purely domestic crime".
Staff Sgt Gordon Black is accused of stealing from a woman, reports the BBC's US partner CBS.
He was not on official travel when he was held on 2 May in the city of Vladivostok, in Russia's Far East.
According to Russian media, Sgt Black was visiting a woman with whom he had a romantic relationship.
National Security Council spokesman John Kirby told reporters the US is "aware of this case and other matters related to Russia".
At the White House briefing on Monday, Mr Kirby said he could not provide more details.
According to a statement from the US Army, the soldier is facing charges of criminal misconduct.
"The Army notified his family and the US Department of State is providing appropriate consular support to the Soldier in Russia," said spokeswoman Cynthia Smith.
The soldier had been in the process of changing duty stations from South Korea back to Fort Cavazos in the US state of Texas, according to CBS.
