Seoul is preparing to coordinate international “countermeasures” in response to North Korea’s claim that it has resumed plutonium production and is continuing to enrich uranium, South Korea’s defense ministry said on Thursday.

The claims, which were issued by Pyongyang’s Atomic Energy Institute in a written interview to Kyodo News, cause Seoul concern because they show North Korea has two active paths to develop more nuclear warheads.

“If the North has reprocessed as reported, it would be in violation of UN Security Council resolutions which prohibit all activities related to the North’s nuclear program,” defense ministry spokesperson Moon Sang-gyun said in