Seoul's Defense Ministry said that North Korea has not conduct high-explosives experiments so far this year.

During parliamentary inspection on the Defense Ministry held Thursday, the ministry's defense intelligence chief Cho Bo-keun made the remark while responding to a question by Saenuri Party lawmaker Han Ki-ho.

High-explosives experiments are essential in the process of miniaturizing nuclear weapons. 

North Korea continued these experiments over the years at its testing site in Yongdeok-dong in capital Pyongyang, which is aimed at accumulating nuclear miniaturization technologies.

South Korean intelligence authorities are known to be closely monitoring the situation as the absence of such experiments may signal that the North has acquired miniaturization technologies.

Defense Minister Han Min-koo added that Seoul is keeping close watch on the North because of its continued efforts to diversify and miniaturize nuclear weapons.