North Korea confirmed the production of plutonium has been restarted in the country after speculations that it reopened its Yongbyon nuclear facility earlier this month . it will continue conducting nuclear tests till perceived threats from U.S. remain.

The Yongbyon reactor was closed down in July 2007. However, North Korean government officials said in September 2015 that the plant was operational again,  it was working on improving the “quality and quantity” of its nuclear weapons. Since then, the Kim Jong Un-led country has carried out several nuclear and missile tests, eliciting stricter sanctions from the United Nations Security Council.

The amount of weapons-grade uranium and plutonium that North Korea holds remains unclear. the plutonium produced at the Yongbyon facility is used in the country’s nuclear bombs.

The Atomic Energy Institute, which controls Yongbyon, said in a written interview with Kyodo: “We have reprocessed spent nuclear fuel rods removed from a graphite-moderated reactor”