Officials in North Korea have arrested an American college student after they say he “was caught committing a hostile act against the state.” Otto Frederick Warmbier—a 21-year-old-student at the University of Virginia—was detained in the airport as he was preparing to leave the country after a 5-day trip organized through a Chinese tourism group. He’s been held since January 2, though the country has just publicized his arrest. His detainment came just days before the North Korean military conducted another highly criticized nuclear bomb test. Warmbier was part of the tour group’s “New Year’s Party Tour,” which visited sites around Pyongyang during New Year festivities, but it’s unclear how he “[aimed] to destroy the country’s unity” as North Korea alleges.