WASHINGTON (NewsNation) — An American soldier visiting a girlfriend in Russia was arrested on charges of stealing from her. He remained in custody Tuesday.

Staff Sgt. Gordon Black, 34, assigned to the U.S. Eighth Army based in South Korea, was set to return home to Fort Cavazos in Texas. Instead, he traveled from Incheon, South Korea, to Russia, for personal reasons, Cynthia Smith, an Army spokeswoman, told NewsNation.

According to the Associated Press, Black, who is married, traveled to see a longtime girlfriend.

Smith said Black did not receive official clearance and the U.S. Department of Defense did not authorize the travel to China and Russia.

“Official and leave travel is currently restricted pursuant to the DoD Foreign Clearance Guide. There is no evidence Black intended to remain in Russia after his PCS leave period ended,” she said.

Black was arrested Thursday in Vladivostok, a major military and commercial Pacific port, on charges of criminal misconduct, Smith said. Russia notified the U.S. and the Army notified the soldier’s family.

The White House said it has remained in contact with Black.

Black is in a pretrial detention facility and will remain in detention until his next hearing pending determination, Smith said.

The Russian woman has lived in South Korea and last fall she and Black had a domestic dispute or altercation, police said. After that, she left South Korea. However, it’s unclear if she was forced to leave or if any Korean authorities were involved in the matter.

Black’s arrest comes as Russia is holding several Americans in its jails, including corporate security executive Paul Whelan and Wall Street Journal reporter Evan Gershkovich. The U.S. government has designated both as wrongfully detained and has been trying to negotiate for their release.

The Associated Press contributed to this report.