North Korea has begun an investigation into the military’s 2nd Corps and 4th Corps as part of its efforts to find out how a North Korean defector slipped over the inter-Korean border and into Kaesong recently, Daily NK has learned. 

The two military units are responsible for guarding the western area of the inter-Korean border, the same area the defector slipped back into the country.

“[The defector reentered the country] near a guard post staffed by civil police from the 2nd and 4th corps,” a source in North Korea told Daily NK on Tuesday. “A joint investigation team made up of about 20 people from the Central Military Commission [CMC] and Organization and Guidance Department [OGD] has been sent to investigate the two units.” 

Soldiers in the 2nd and 4th Corps are responsible for patrolling areas right at the edge of the Military Demarcation Line (MDL). These areas have mines buried underground or – in specific areas where there are high-voltage wires – there is monitoring equipment, including closed-circuit television (CCTV) systems. This means that surveillance of these areas largely rely on patrols conducted by soldiers in the two units. 

Daily NK understands that North Korean authorities were unaware that the defector had escaped until he was arrested by the Ministry of State Security (MSS) in Kaesong. This has reportedly led to close scrutiny of why front line border patrols failed to detect the man’s crossing and whether there was “lax discipline” among members of the 2nd Corps and 4th Corps.

Daily NK’s reporting also revealed that the defector was arrested after he turned himself in. It was only after his arrest that the authorities discovered that he had defected from the country three years ago, along with the route he used to enter South Korea. 

“The joint investigation team is currently looking into the incident, and has been instructed to submit a report to the Party by Aug. 5,” the source said. “Civil police officers and soldiers are saying that the Party has spent money to install a dense network of [surveillance] equipment along the [Sino-North Korean] border to stop defections and anyone trying to enter the country. They have noted, however, that there is a lack of such equipment and systems near the MDL.” 

North Korean media recently reported that an emergency meeting of the ruling party’s politburo on July 25 “sternly” pointed out border guards had done a poor job of patrolling the area where the man had crossed over the border and that the Central Military Commission should hand down strong punishments and implement strong measures to prevent a repeat of the incident after, of course, the results of an “intensive investigation” into the units responsible have been finalized. 

According to the source, the defector’s testimony could lead to punishment of civil police officers and other officials who had worked in both the areas where the man had defected three years ago and where he crossed over the border again more recently. 

The 2nd and 4th corps commanders, along with the highest-ranking political and security officials in the two units, are not likely going to be fired because of a “trivial” issue concerning a defector, the source speculated, citing rumors he had heard. 

While the investigation is taking place, the 2nd and 4th corps have reportedly been placed under a so-called “top combat-ready posture.” Other front line units, the 1st and 5th corps, along with the border patrol on the Sino-North Korean border, have also been ordered into a “special alert posture,” which is one level below the “top combat-ready posture,” according to the source. 

Units on the inter-Korean border have reportedly been ordered to 1) “thoroughly” and “with vigilance” perform their duties related to guard posts, trenches, and “artillery positioning”; 2) conduct even more frequent patrols along the border – once per hour, instead of the normal once per two to three hours; and, 3) “recheck” the surveillance equipment along the entire MDL while ensuring their military strength is “100%.” 

“This alert posture is likely to remain in place until Aug. 10, but may be extended further,” the source said.

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Ha Yoon Ah is one of Daily NK's full-time journalists. Please direct any questions about her articles to