John Bolton was called a "defective human product" (Picture: PA).
North Korea has called the US National Security Adviser John Bolton a "warmonger" and "defective human product".
The statement by an unnamed North Korean foreign ministry spokesman came as US President Donald Trump continued his visit to Japan for meetings with Prime Minister Shinzo Abe, in which the nuclear standoff with North Korea was expected to be high on the agenda.
It comes after Mr Bolton called the North's recent tests of short-range missiles a violation of UN Security Council resolutions.
He told reporters in Tokyo on Saturday there was "no doubt" North Korea's recent launches violated UN resolutions, and that sanctions against the North must be kept in place.
Mr Trump later downplayed the missile tests, tweeting:
"North Korea fired off some small weapons, which disturbed some of my people, and others, but not me."
North Korea tested short-range ballistic missiles on 4 and 9 May, ending a pause in launches that began in late 2017.
The tests have been seen as a way for North Korea to pressure Washington to soften its stance on easing sanctions against it without causing negotiations to collapse.
In the statement carried by Pyongyang's official Korean Central News Agency, the North Korean spokesman said the North was rightfully exercising its rights of self-defence with the launches.
The spokesman said John Bolton was an "ignorant" hard-liner who, throughout different US administrations, constantly pushed provocative policies against North Korea, which the spokesman said included endorsements of pre-emptive strikes and regime change.
The spokesman also said that Mr Bolton's "hammer act" was responsible for the collapse of a major nuclear deal between the countries reached in 1994, when the North agreed to halt its nuclear programme in exchange for US fuel aid.
The deal broke down in 2002 after US intelligence agencies said North Korea was continuing its pursuit of bombs with a secret uranium enrichment programme.
The spokesman continued:
"Bolton should not be called a security adviser who works to secure security, but an adviser for security destruction who destroys peace and security".
"It's not that strange that crooked sound will always come out the mouth of a man who is structurally flawed, and it's best that this defective human product goes away as soon as possible."