A U.S. Navy officer is in custody at a military prison under charges of espionage, White House spokesman Josh Earnest said on Monday.

The officer is being held at the Navy Consolidated Brig in Chesapeake, Virginia, Earnest said.

He declined to comment on the “substance of the allegations” and referred reporters’ questions about allegations of the officer passing sensitive U.S. intelligence and state secrets to other countries to the Department of the Navy.

A U.S. official told Reuters on Sunday that a U.S. Navy officer with access to sensitive U.S. intelligence faces espionage charges over accusations he passed state secrets, possibly to China and Taiwan.