North Korea slams 'war maniac' John Bolton
John Bolton appears on CNN (screen grab)

North Korea slammed US National Security Advisor John Bolton on Monday, calling him a "war maniac" and "war monger", just as President Donald Trump offered a positive outlook on relations with Pyongyang.

Talks between Washington and Pyongyang have been deadlocked since the collapse of a summit between Trump and North Korean leader Kim Jong Un in Hanoi in February when they failed to agree a deal on denuclearisation.

The North has since sought to raise the pressure and carried out two short-range missile tests earlier this month.

Bolton said Saturday there was "no doubt" they violated UN Security Council resolutions against ballistic missile launches, but insisted Washington was still ready to resume talks.

A spokesman for the North's foreign ministry dismissed Bolton's remarks, saying Pyongyang had never recognised the UN bans on ballistic technology, which denied the "rights to existence and development of a sovereign state".

"His claim is indeed much more than ignorant," he said in a statement carried by the official Korean Central News Agency (KCNA).

Without referring to the weapons as missiles, the statement said the launches did not target or threaten any neighbouring countries.

Banning launches using ballistic technology is "tantamount to a demand that the DPRK should give up its self-defensive right," he said, using the acronym for the North's official name.

The spokesman went on to denounce Bolton, calling him a "war maniac" who developed various "provocative policies" against the North after the Bush administration designated it part of the Axis of Evil along with Iran and Iraq in 2002.

He accused the hawkish official as starting the Iraqi war and leading efforts to scrap the Intermediate-range Nuclear Forces Treaty between the US and Russia, "that has served to ensure peace in Europe for decades".

"He is now gaining notoriety as a warmonger for his obsession with other wars in the Middle East and South America," the spokesman added.

"It is not a mere coincidence that criticisms are now being heard in the US that Bolton is a warmonger whispering war to the President when he himself evaded military service, saying he had no desire to die in a Southeast Asian rice paddy," he added.

Calling Bolton "structurally defective", he added that the US official was "a security-destroying adviser who is wrecking peace and security".

The statement came just minutes after Trump -- on a visit to Japan -- said there was "great respect" between the United States and North Korea and predicted "lots of good things".

Trump expressed confidence in his relationship with Kim at the weekend and downplayed Pyongyang's recent missile launches, calling them "small weapons" that "disturbed some of my people, and others, but not me".

Last week, KCNA launched a diatribe against Democratic former US vice president Joe Biden, calling him an "imbecile" and a "fool of low IQ", prompting White House spokeswoman Sarah Sanders to say that Trump agreed with the assessment.