North Korea has begun building a wall at several locations near to the border with South Korea, the BBC reports.
Satellite images show that land in the demilitarized zone (DMZ) has been cleared, which experts say may be a violation of the long-standing truce with South Korea.
The DMZ is a 4 km wide buffer zone between North and South Korea, which are technically still at war as they have never signed a peace treaty. It is divided into two, each side controlled by respective nations.
Satellite images show at least three sections where barriers have been erected near the demilitarized zone, covering a total of about 1 km near the eastern edge of the border. It is not clear when the construction of the facilities began.
In the 1990s, North Korea built anti-tank walls to deter a tank advance in the event of a war.
South Korean military said it has identified ongoing activity related to strengthening tactical roads, laying mines and clearing wasteland.
According to Edward Howell, a researcher on the Korean Peninsula at Oxford, warming relations between North Korea and the Russian Federation will lead to more provocations by Pyongyang.