For years, North Korean defectors have used free speech protections of their new home in South Korea to taunt the regime in Pyongyang. Now, South Korean President Moon Jae-in believes some have taken it too far.

Two brothers who led prominent defector groups were questioned by police last week, after Moon’s administration sought to have them prosecuted over leaflets they sent north of the border. Previously, Park Sang-hak and Park Jung-oh chiefly had to worry about threats from Kim Jong Un, whose regime has denounced them as "human scum,” dubbing the elder Park "Enemy Zero.”

The episode has thrust North Korean defectors — and Moon’s uneasy relationship with them — back into the spotlight. While Moon entered politics seeking both stronger human rights protections and a better relationship with North Korea, he has often found himself as president prioritizing ties with Pyongyang over the abuses highlighted by defectors.