North Korea has likely increased its stockpile of plutonium for nuclear weapons, according to South Korea’s new defense white paper, the first time Seoul has reported an increase in six years.

The report released Thursday states Pyongyang has around 70 kg of the fissile material as of Dec. 2022, up from the previous white paper’s estimate of 50 kg in 2020 and reportedly enough for around a dozen nuclear warheads.

But an expert cautioned that the new estimate doesn’t necessarily mean that the DPRK processed 20 kg of plutonium in just the last two years, pointing to problems with how