This captured image from a surveillance camera recording shows North Korean soldiers blowing up a part of Gyeongui Road, a road linked to South Korea on the western side of the Korean Peninsula, Tuesday. Courtesy of Joint Chiefs of Staff

North Korea said Thursday its constitution clearly defines South Korea as a "hostile state," highly suggesting that Pyongyang has amended its constitution in line with leader Kim Jong-un's order to codify the South as an enemy, not a partner for reconciliation and unification.

The Korean Central News Agency (KCNA) made the report while reporting on the North's blowing up earlier this week of roads and railways connected to South Korea that were once considered key symbols of inter-Korean reconciliation.

"This is an inevitable and legitimate measure taken in keeping with the requirement of the DPRK Constitution which clearly defines the ROK as a hostile state, and due to the serious security circumstances running to the unpredictable brink of war owing to the grave political and military provocations of the hostile forces," the KCNA reported in an English-language article.

ROK and DPRK stand for the official names of South Korea and North Korea, respectively: the Republic of Korea and the Democratic People's Republic of Korea.

South Korea condemned the potential constitutional revision, reaffirming that it will strongly respond to any further provocations by the North.

"This action is anti-unification and anti-national by betraying the hopes of the South Korean people and North Korean residents for unification, which the government strongly condemns," the unification ministry said.

Last week, North Korea convened a key parliamentary meeting and revised its constitution, yet had remained silent whether leader Kim's "two hostile states" was included in the revision or removed unification-related clauses in line with Kim's order.

Last December, during a year-end party meeting, Kim described inter-Korean relations as those between "two states hostile to each other" and stated that reconciliation or unification with South Korea was no longer a goal.

In January, Kim called for revising the constitution to define South Korea as its "invariable principal enemy." He also ordered officials to take steps to "physically and completely" cut off the railway tracks to an "irretrievable level."

Under a 1991 inter-Korean accord, known as the Basic Agreement, relations between South and North Korea are defined as a "special relationship" tentatively formed in the process of seeking reunification, not as state-to-state relations.

Friday's report did not provide further details about the constitutional changes, but it is widely expected that the major points of the revised constitution will be revealed through other means in the future.

On Tuesday, South Korea's military announced that North Korea has blown parts of its roads, after North Korea said it would permanently block its border with South Korea and build front-line defense structures.

North Korea blows up parts of the Gyeongui and Donghae roads connected to South Korea, in this photo released by North Korea's official Korean Central News Agency, Oct. 17. Yonhap

The Koreas are connected by roads and railways along the Gyeongui Line, which connects the South's western border city of Paju to the North's Kaesong, and the Donghae Line along the east coast.

The KCNA said Thursday that parts of both roads and the railway in Gangwon Province along the east coast and part of the roads and railways in Kaesong "have been completely blocked through blasting."

North Korea said the move was "part of the phased complete separation of its territory" and said it "will continue to take measures to permanently fortify the closed southern border."

A South Korean government official speculated that the North might construct concrete walls over the roads that were damaged.

"Since the term 'permanently fortify' was used, it's likely that they will extend this action by building concrete barriers," said the unification ministry official on the condition of anonymity.

In August, North Korea severed the Gyeongui and Donghae railways.

The routes, largely funded by South Korea, had been seen as key symbols of past inter-Korean reconciliation efforts and were regarded as a project of personal interest to Kim's grandfather and the founder, Kim Il-sung.

Observers suggest that the destruction of the railways and roads, which were already in disuse, seems to be a symbolic act by North Korea to signal both domestically and internationally that inter-Korean relations have come to a complete end.

"The intention to permanently fortify the southern border reflects North Korea's resolve to institutionalize the hostile state," said Yang Mu-jin, president of the University of North Korean Studies.

Tensions along the inter-Korean border have risen in recent weeks after Pyongyang accused Seoul of sending drones carrying anti-North Korean propaganda leaflets over the capital. South Korean Defense Minister Kim Yong-hyun, however, stated that he could not confirm the North's allegations. (Yonhap)