North Korea says it has detained a US citizen on suspicion of hostile acts against the state. The North's official news agency KCNA said Kim Hak Song worked at the Pyongyang University of Science and Technology (PUST) and was was detained on Saturday. Song is the fourth American citizen in North Korean custody.<br/> <br/>In a statement, the U.S. State Department said, they are in touch with the Swedish Embassy in Pyongyang, to try to secure the release of US citizens. The detention comes amid heightened tensions between North Korea and the US.