The South Korean assessment on the North's arsenal is not much different from various outside civilian estimates largely based on the amount of nuclear materials that North is believed to have produced.
According to South Korean government reports, the North is believed to have produced 110 pounds of weaponized plutonium, enough for at least eight bombs.
Stanford University scholars, including nuclear physicist Siegfried Hecker who visited North Korea's centrifuge facility at Nyongbyon in 2010, wrote earlier this year that North Korea is estimated to have a highly enriched uranium inventory of 550 to 1,100 pounds, sufficient for 25 to 30 nuclear devices.
Many foreign experts say North Korea are likely running additional secret uranium-enrichment plants.
The North entered talks with the United States and South Korea earlier this year, saying it's willing to negotiate away its advancing nuclear arsenal.