North Korea has been dismantling power lines installed just north of the shared border with the South from Sunday in the latest of a series of demolitions of past inter-Korean peace efforts.

According to South Korea’s Joint Chiefs of Staff on Tuesday, the North Korean military was spotted taking down power transmission systems on its side of the Military Demarcation Line dividing the Korean Peninsula.

The JCS said the North Korean military cut off high-voltage wires from the transmission towers that deliver electricity to Kaesong Industrial Complex, an inter-Korean cooperation site that has long been defunct.

The industrial park opened in 2004 as a joint project for economic cooperation and reconciliation. Seoul closed it down in 2016 following a Pyongyang rocket launch.

“The North Korean military took down high-voltage wires from one of the power towers closest to the border. We don’t know whether they will do the same with the rest of the towers. These are properties that South Korea paid for and built,” JCS spokesperson Col. Lee Sung-jun told reporters.

North Korea in October blew up inter-Korean roads connected to the South on each side of the Korean Peninsula. The South’s JCS at the time explained that the explosion was not destructive enough to destroy anything beyond the surface of the roads, seeing the move as largely symbolic.

The South Korean military believes the cross-border aggression is a continuation of North Korean leader Kim Jong-un threatening to abandon the traditionally shared goal of unification, and declaring the relationship between the two Koreas to be that of two hostile countries in January.