North Korea launched several ballistic missiles toward the Yellow Sea on Monday afternoon, Seoul's military said, on the first day of a large-scale joint U.S-South Korea military exercise on the Peninsula.

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.

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 multiple ballistic missiles off its west coast Monday, South Korea’s military said, as Pyongyang shows little sign of holding back from its missile testing following Donald Trump’s return to power.