A group of twenty North Koreans defected across the Yalu River in the first week of September, marking the largest known group defection since the launch of the Kim Jong Eun regime.

A Yangkang Province source told Daily NK on Friday, “Twenty North Koreans from Hyesan crossed the river in a group on the 7th. I hear that the departure was carefully planned ahead of time.”

The source withheld further details due to concerns that the National Security Agency might use open source information to try and track the group, but did acknowledge, “There are some children and old people; members of seven families left together.”

According to the source, it was empty houses that initially aroused suspicions and led to reports reaching the security services, but the Hyesan branch of the National Security Agency did not take it seriously until four days after the families had left. The authorities are currently trying to track the twenty, while also investigating whether which border guards helped to facilitate the defection.

The source also told Daily NK that he expects the incident to cause quite a stir domestically.

Notably, this is because not only is it the largest group defection since the Kim Jong Eun era began, but it is also comparatively rare for large groups of people to cross the river en masse (although defecting separately then banding together in China is not uncommon).

Those in Hyesan who have already learned about the case apparently regard it as the result of continuing economic difficulties despite political propaganda about economic change. They add that the lives of ordinary citizens haven’t changed much since the regime changeover of December 2011.