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.

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.

The comments have sparked fears the US might favour talks on nuclear arms reduction with North Korea instead of full denuclearisation.

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."

US President Donald Trump stated that he still maintains good relations with North Korean leader Kim Jong Un, with whom he held several summits during his first term. The White House leader once again referred to North Korea as a "nuclear state,

U.S. President Donald Trump claimed Thursday to have a "great" relationship with North Korean leader Kim Jong-un, and described the recalcitrant country as a "nuclear power," as he has voiced openness to reengaging with the dynastic ruler.