He Sends Up Balloons, and North Korea Wants Him Dead

SEOUL—A black car rolled into the parking lot in southern Seoul, and three men stepped out into the summer heat. Two of the men were police officers, even though you couldn’t tell from their appearances. The third was the man they were there to protect: Park Sang-hak, a North Korean defector now living in South Korea and sometimes referred to as “Enemy Zero” by the North.

“I’ve already almost died twice,” Park casually said last week from a park bench where he escorted Foreign Policy and other international journalists. In...