Pyongyang's military last week vowed to permanently seal its southern border after spending months laying mines and building anti-tank barriers in the wake of leader Kim Jong Un declaring the South his country's "principal enemy."
The North's KCNA news agency reported road and rail links with South Korea were now completely blocked off after blasting large sections of them on Tuesday as legitimate action taken against a hostile state as defined by its constitution.
North Korea blew up sections of inter-Korean roads and rail lines on its side of the heavily fortified border between the two Koreas on Tuesday, prompting South Korea's military to fire warning shots.
North Korea's military on Tuesday reportedly destroyed the Gyeonggi and Donghae roads near the demilitarized zone dividing the Korean Peninsula.