North Korea has deployed amphibious landing crafts to the frontline as the country keeps up its tight combat readiness despite on-going inter-Korean talks to defuse military tension, military sources said Monday.

About 10 North Korean air-cushioned landing crafts have left their home base in Cholsan, North Pyongan Province, and come forward to the Goampo naval base, located about 60 kilometers north of the Northern Limit Line in the Yellow Sea, the de facto inter-Korean sea border, the sources said. 

"Since North Korea declared a semi-war state, its infiltration vehicles and forces have been actively moving," one of the sources said.

North Korea has two types of air-cushioned boats. One of them is the 35-ton class Gongbang II that can travel at a speed between 74-96 kmph, and the other is the 20-ton class Gongbang III that can travel up to 96 kmph.

With the mission to transport special infiltration forces ashore, the air-cushioned vehicle is one of North Korea's three core infiltration assets.

The North has also deployed the other two infiltration forces -- submarines and special artillery troops -- near the border as the country followed the quasi-war declaration up with a tougher combat readiness posture.

On Friday, North Korean leader Kim Jong-un declared a "quasi-state of war," threatening that the country is prepared to go to "all-out war" as inter-Korean military tension has escalated after the two countries exchanged artillery shells over the border a day earlier.

As the countries were brought to the brink of a military confrontation, the two Koreas launched rare high-level government talks Saturday to defuse the situation, with no major progress having been reported so far.

While the talks continued, the North Korean army has leveled up its combat readiness to match the intensity required under the manual of a semi-war state, one of the sources said.

"Since the North declared a quasi-war condition, every move of the North Korean army is being detected by the joint surveillance assets of South Korea and the United States," the source said. (Yonhap)