North Korea has unveiled for the first time what it says is a nuclear-powered submarine under construction, a weapons system that can pose a major security threat to South Korea and the US.

North Korea has long vied for nuclear-powered submarines, which would allow it to fire missiles from underwater. Advanced detection of the weapons is difficult, making the country’s construction of the warships worrisome.

The AUKUS Submarine Industry Strategy states, “The [AUSSQ Pilot program] will use a B2B model, enabling HII Australia to work directly with Australian businesses to qualify both the businesses and their products, and subsequently assist them to tender for supply into the US programs.”