(PYONGYANG, North Korea) — North Korea has detained a U.S. citizen, officials said Sunday, bringing to three the number of Americans now being held there. Tony Kim, who also goes by his Korean name Kim Sang-duk, was detained on Saturday, according to Park Chan-mo, the chancellor of the Pyongyang University of Science and Technology. Park said Kim, who is in his 50s, taught accounting at the university for about a month.