After inspecting a nuclear-material production facility, Kim also warned of an "inevitable" confrontation with hostile nations and said 2025 would be a "crucial year" for bolstering North Korea's nuclear forces, the KCNA news agency said.

"It is our firm political and military stand and invariable noble task and duty to develop the state's nuclear counteraction posture indefinitely," Kim said, according to KCNA.

The report, and Kim's nuclear factory visit, follow Pyongyang's test-firing on Saturday of sea-to-surface strategic guided cruise missiles, its first weapons test since Trump returned to the White House on January 20.

North Korea says it is seeking nuclear weapons to counter threats from the United States and its allies, including South Korea.

The two Koreas remain technically at war since the 1950-1953 conflict ended in an armistice, not a peace treaty.

Relations between Pyongyang and Seoul have been at one of their lowest points in years, with the North launching a flurry of ballistic missiles last year in violation of United Nations sanctions.

Trump, who had a rare series of meetings with Kim during his first term in office, said in an interview last week that he would reach out to the North Korean leader again, calling Kim a "smart guy".

On Wednesday, KCNA said Kim addressed "the world's most unstable situation in which a long-term confrontation with the most vicious hostile countries is inevitable", and that it was "indispensable for the country to steadily strengthen the nuclear shield".