PYONGYANG, North Korea — North Korea’s highest court sentenced an American tourist to 15 years in prison with hard labor for subversion on Wednesday, weeks after authorities presented him to media and he tearfully confessed that he had tried to steal a propaganda banner.

Otto Warmbier, a University of Virginia undergraduate, was convicted and sentenced in a one-hour trial in North Korea’s Supreme Court.

He was charged with subversion under Article 60 of North Korea’s criminal code. The court held that he had committed a crime “pursuant to the U.S. government’s hostile policy toward (the North), in a bid to impair the unity of its people after entering it as a tourist.”

North Korea regularly accuses Washington and Seoul of sending spies to overthrow its government to enable the U.S.-backed South Korean government to take control of the Korean Peninsula.

Tensions are particularly high following North Korea’s recent nuclear test and rocket launch.