The North has already warned that it intended to being turning its spent nuclear fuel rods into plutonium in protest at the international criticism of its rocket test on April 5. Yongbyon is thought to be capable of processing 200 to 250 tons of spent fuel each year and harvesting around 100kg of plutonium. In the past, the US has warned that reprocessing fuel is an action that could lead to a military strike on the country.