North Korea has been holding a Korean-American missionary, Kenneth Bae, since November 2012. Bae was sentenced to 15 years of hard labor for what the North has claimed were hostile acts against the state. In March, it deported an Australian missionary detained for spreading Christianity in the country after he apologized for anti-state religious acts and requested forgiveness.
The announcement Saturday came as President Barack Obama was visiting rival South Korea. Obama warned North Korea that it would face tougher sanctions if it follows through with threats to conduct a fourth nuclear test.