An American man sentenced to 15 years hard labor in North Korea for attempting to steal a propaganda poster has not been permitted consular access in nearly six months, the U.S. State Department confirmed Wednesday.

Otto Warmbier, a 21-year-old college student at the University of Virginia, was detained in January as he prepared to leave North Korea at the end of a tour. He was sentenced in March for swiping the poster and for other unspecified "crimes against the state."

Washington has criticized the sentence as "unduly harsh."