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 denounced joint military drills between the US and South Korea saying the South Korean Air Force’s recent bombing mistake shows the risk of the region unintentionally getting dragged into a new armed conflict.

In a statement issued via state media on Monday, the North Korean Foreign Ministry called the Freedom Shield drills "a dangerous provocative act of leading the acute situation on the Korean peninsula, which may spark off a physical conflict between the two sides by means of an accidental single shot, to the extreme point."

North Korea fired several ballistic missiles into the sea on Monday in what was the latest display of the communist country’s military capabilities. The missile launches were reportedly in response to the joint military drills conducted in the region between the U.