The submarine could significantly escalate security concerns on the Korean peninsula and in the Taiwan Strait, experts say North Korea's construction of a nuclear-powered submarine could significantly escalate security concerns on the peninsula and in the Taiwan Strait,

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.

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.