North Korea has detained another United States citizen, bringing the number of American citizens being held there up to three. The man, Tony Kim, also known as Tim Sang-duk, was detained on Saturday by officials at Sunan International Airport in Pyongyang as he was trying to leave the country. According to the Washington Post, the Korean-American taught accounting at a university in North Korea for about a month. Kim was trying to leave with his wife on a flight to China, said a university spokesperson. The reason for this detainment is unknown at this time.