South Korea’s Defence Ministry has voiced concerns about the military activity of its northern neighbour, communist North Korea, with which it is still technically at war.

The ministry has noted that North Korean engineers are at work at several points along the so-called Demilitarised Zone (DMZ), the line of control dating from the 1953 armistice that ended fighting in the Korean War.

North Korea has been emboldened by an alliance with Russia, and resourced with money from arms sales and the leasing of troops to its ally. It has also observed the Chinese strategy of incremental annexation of the South China Sea. Analysts believe that North Korea is taking the opportunity presented in the current geopolitical moment to test the resolve of its opponents and seek out strategic advantages over them.

Choo Jae-woo, a foreign policy expert at Kyung Hee University in Seoul, commented: “They are testing the limits. They know they have the support of both Russia and China in all their endeavours – military, economic, geopolitical – and Pyongyang feels that now is the time to see how far it can go.”

“We see this elsewhere, in the way the North is building advanced new warships, and it would not surprise me if we started to see similar testing of [the Northern Limit Line] in the West Sea,” he said. The Northern Limit Line is a maritime border that is disputed in a similar manner to the land borders.

The more aggressive posture is not only linked to the global environment but also to a change in North Korea’s stated view of the North-South relationship. It now no longer formally sees the situation as motivated by the need to unify a divided people, but as tension between two hostile countries.

North Korean engineers have largely concentrated on building fortifications such as anti-tank barriers and minefields in areas under its jurisdiction. A recent communiqué from the United Nations Command (a Korean War legacy institution uniting South Korea and its allies) has said that these do not for the most part amount to violations. However, there is concern that the activity is edging closer towards the DMZ, testing what the South will find acceptable.

South Korea’s military has said that in some places, construction has been undertaken less than 100 metres from the halfway point of the DMZ, which it claims is a violation. Moving military capabilities closer to the border between the two countries would nullify the rationale behind the DMZ, and would constitute a dangerous escalation.

Part of the North’s new posture has been to see the middle of the DMZ as its southern border, and it apparently wants to exert control over territory that has historically been a buffer zone.

The Korean peninsula is a flashpoint whose detonation would have global consequences. Since 1953, border incidents have claimed hundreds, and perhaps thousands, of lives (statistics are difficult to establish because of very sparse data from North Korea). North Korea’s reclusiveness and the eccentricity of its ruling dynasty complicate understanding its internal dynamics and motivations – this makes managing tensions particularly challenging.