North Korea can get all the uranium it needs for nuclear weapons through its existing Pyongsan mill, and satellite imagery of tailings piles suggests the country can produce far more nuclear fuel than it is, a new academic study concludes.

Despite a self-imposed moratorium on nuclear weapons tests since 2017, North Korea has said it is continuing to build its arsenal — and this year appeared to have restarted a reactor widely believed to have produced weapons-grade plutonium.

According to research published last month in the journal Science & Global Security by researchers at Stanford University and an Arizona-based mining consulting company, North Korea may be able to increase production and has no need for other uranium mills.