SEOUL, 25th December 2015 (WAM) — North Korea is capable of producing a nuclear weapon with less than 6 kilograms of plutonium, revising down its earlier estimate, South Korea’s intelligence sources said Friday.

While it usually takes 6 kilograms of plutonium to produce a nuclear weapon, the amount could be lower considering the development of technology in North Korea, implying that Pyongyang is capable of producing such a weapon with 5 kilograms, according to multiple government sources cited by South Korea’s news agency Yonhap.

South Korea estimates the North currently holds around 40 kilograms of plutonium, which can produce around eight nuclear weapons. Other sources added North Korea may have increased its holding of plutonium over the past months.

The sources added that North Korea is struggling to produce highly enriched uranium (HEU), although the details were not disclosed.