The Defense Ministry suspects North Korea has up to 50 kilograms of weaponsgrade plutonium and has built six to seven nuclear bombs.

Military sources said that Defense Minister Yoon Kwang-ung called a meeting of top military officials on October 10th, the day after the North conducted the first nuclear test.

The sources added that the ministry and the Joint Chief of Staffs decided to improve contingency plans against North Korea.

At the meeting, a military think tank analysis said that the estimated weight of the North's nuclear weapons would be two to three tons each, addding that the North has deployed 82 bombing units capable of carrying such nuclear weapons at Uiju and Jangjin bases.