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.

U.S. President Donald Trump said on Thursday he still has a good relationship with North Korean leader Kim Jong Un, with whom he held several summits during his first term, and referred to North Korea once again as a "nuclear power.

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 condemned an ongoing U.S.-South Korea joint military exercise Wednesday, saying another incident like Seoul's recent accidental bombing of its own village near the DMZ could lead to "a new armed conflict.

The US and South Korea paused their live-fire drills after the incident but the Freedom Edge 25 drills will continue through March 20 as per schedule

North Korea has issued a sharp rebuke over the major military exercise being carried out by the U.S. and its South Korean ally, labeling the training a "war rehearsal." Newsweek reached out to the Pentagon and the South Korean embassy in the U.