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 on March 8 released images of leader Kim Jong-un inspecting the construction of what it calls a “nuclear-powered strategic guided missile submarine,” marking its first public acknowledgment of the project.

Last week's accidental shelling of a South Korean village occurred less than 20 miles from the border of the nuclear-armed North.