In June last year, North Korean troops violated the border three times, prompting South Korea to fire warning shots. The incidents occurred when the Koreas were embroiled in Cold War-style campaigns like balloon launches and propaganda broadcasts, but they didn’t develop into a major source of tensions.

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

High - tension as South Korean troops open fire to warn patrolling troops from the North who make suspected bungle and accidentally wander across the most heavily militarised border in the world