Observers claimed the Pyongyang troops might have mistakenly crossed the boundary while fortifying their side with anti-tank barriers or mines.

South Korea's military fired warning shots on Monday after approximately 10 North Korean soldiers crossed the heavily fortified border that separates the two countries, an incident that underscores rising tensions on the Korean Peninsula amid political instability in Seoul and continued provocations from Pyongyang.

South Korea's military fired warning shots after North Korean soldiers crossed the military demarcation line. The soldiers, some of whom were armed, returned after the incident, which may have been a mistake during reconnaissance activities.