South Korea has boosted construction of new paths and lookouts throughout the demilitarized zone (DMZ) in recent months, according to NK Pro analysis of satellite imagery, in what appears to be a response to North Korea’s new border-wide fortification project.

The activity on both sides of the military demarcation line (MDL) in the DMZ comes as ROK President Lee Jae-myung calls for reviving an inter-Korean military agreement, underscoring the thorny reality on the ground that could complicate efforts to reduce border tensions. 

An NK Pro review of recent Planet Labs imagery of the inter-Korean border found several previously unreported areas of construction on the ROK side close to the MDL, unrelated to guard post (GP) restoration, as well as continued work on the DPRK side at over a dozen locations.

In many cases, the work has continued on both sides in the months since the newly elected liberal ROK leader took office in early June.

The recent additions could disrupt possible plans for re-withdrawal from the DMZ, though Pyongyang has also shown no signs of reciprocating or returning to the agreement, under which both sides dismantled a portion of guard posts.

Just last week, Lee said in a major speech that “to prevent accidental clashes between South and North Korea and to build military trust, we will take proactive, gradual steps to restore the September 19 Military Agreement,” also known as the 2019 Comprehensive Military Agreement (CMA).

The ROK military previously confirmed in late June that it had restored 11 GPs inside the DMZ, after announcing the project last October. 

Pyongyang and Seoul signed the CMA during the administration of liberal President Moon Jae-in, each agreeing to destroy 10 GPs and withdraw from an additional one. 

Former ROK President Yoon Suk-yeol, who adopted a hardline anti-DPRK policy stance, partly withdrew from the CMA in late 2023 in response to a North Korean military satellite launch, to which Pyongyang responded by redeploying soldiers and weapons to the DMZ.

North Korea also announced this June that it was continuing fortification activities in the DMZ. The project — part of DPRK leader Kim Jong Un’s flip to opposing unification and “permanently” separating the two Koreas — began in spring 2024 and continued throughout last year until pausing over winter.

Though the 1953 Armistice Agreement stipulates that all sides must “withdraw all of their military forces, supplies and equipment from the demilitarized zone,” both Koreas have built up GPs, roads, paths and fence lines inside the DMZ in the decades since.

The activity is so common that despite former President Yoon’s alleged efforts to bait North Korea into armed conflict last year, his military command did not publicly complain when one of the DPRK’s newly carved paths crossed the MDL onto the South Korean side. An ROK defense ministry official told NK Pro the MDL’s true coordinates were “classified,” a claim rejected by experts.

Planet Labs imagery shows North Korea building more new paths at the end of 2024 and since May this year parallel and very close to the MDL, possibly as a prelude to building walls or fences.

DPRK soldiers also resumed building the longest straight and flat section of new border wall in early August, cutting the ruins of the 10th-century walled capital of the Taebong kingdom in half. 

The imagery shows that activity on the ROK side includes a large cleared area on a mountaintop near Kumgang on the east coast, which could be built into a new GP.

South Korea has also carved out new paths in the mountains near existing and newly restored GPs.

The ROK defense ministry told NK Pro last week that it “has nothing to confirm” about recent construction in the DMZ.

Choi Gi-il, a former ROK Army lieutenant colonel and military studies professor at Sangji University, told NK Pro that the purpose of the ROK construction appeared intended to improve “maintenance and surveillance” of North Korean activities across the MDL.

Satellite imagery also supports the conclusion that the ROK construction was in many cases meant to establish new visual lines of sight on changing North Korean positions, as it followed new construction nearby on the DPRK side.

As of mid-August, new North Korean paths, walls and fences have been built along a significant portion of the MDL, closer to the line than either side had previously built, though not in all areas. 

South Korea’s construction has been much more sparse, appearing to be paths and roads for transportation and ease-of-movement purposes, while it has not involved new walls or fences close to the MDL.

Jooheon Kim contributed reporting to this article. Edited by Bryan Betts.