The arrest of a U.S. citizen by North Korea on Saturday — the second of an American national in two weeks — could be a prelude to more provocations by Pyongyang amid already surging tensions on the Korean Peninsula, an expert on the regime of leader Kim Jong Un has said.

The North's state-run Korean Central News Agency said in a brief dispatch Sunday that Kim Hak Song had been detained Saturday for unspecified "hostile acts" against the country and that "a relevant institution is now conducting detailed investigation into his crimes."

Kim Hak Song worked at Pyongyang University of Science and Technology (PUST), the same place of work as another U.S. national, accounting instructor Kim Sang Dok, whose detention was announced last Wednesday.