AFP reported that on October 9, North Korea announced that it would take a "permanent" step to close its border with South Korea and notify the US military to prevent the possibility of an unintended collision.
A statement from Pyongyang said they would "completely cut off all roads and railways" that were expected to facilitate future travel between the two Koreas.
While North Korea sees this as a "major military move," one analyst said it could just be a continuation of a process that has been in the works for some time.
Inter-Korean relations are at their most tense in years, with North Korea closing down reunification agencies and declaring South Korea its "main enemy."
There had been speculation that North Korea would scrap the 1991 inter-Korean agreement during the parliamentary session that ended on October 8. However, in an official report on October 9, North Korean state media did not mention the termination of the agreement.
Instead, the North Korean military said it would take a "significant military step" by completely cutting off all links with South Korea and bolstering defenses on the southern border.
Pyongyang also said it had sent a message to the US forces to avoid misjudgments and prevent unwanted conflicts over the new defense project in the sensitive border area.
Despite being one of the most heavily militarized borders in the world, a North Korean managed to cross into South Korea in August.
Seoul said that since July, Pyongyang has carried out a series of activities such as planting mines and erecting barriers, turning the area into a "wasteland" along the border. In June, the South Korean military also said that several North Korean soldiers were killed in mine explosion accidents while carrying out border reinforcement missions.
At the same time, South Korea's intelligence agency discovered that North Korea was destroying part of the Donghae railway connecting the two Koreas. Yang Moo-jin, president of the University of North Korean Studies in Seoul, said the destruction was aimed at completely cutting off the connection with South Korea, and the recent announcement was "official confirmation."
Amid rising tensions, Pyongyang said its move was a "self-defense measure" against South Korean military drills and the presence of strategic nuclear assets from the United States.
