The statement by a North Korean foreign ministry spokesman came as President Donald Trump continued his visit to Japan for meetings with Prime Minister Shinzo Abe, in which the nuclear stand-off was high on the agenda.

Bolton told reporters on Saturday there was "no doubt" North Korea's recent launches violated UN resolutions and sanctions must be retained.

North Korea tested short-range ballistic missiles on May 4 and 9, 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 without actually causing the negotiations to collapse.

In the statement, carried by Pyongyang's Korean Central News Agency, the spokesman said the North was rightfully exercising its right to self-defence.

"Demanding us to ban all launches using ballistic technology regardless of range is same with asking us to relinquish our rights for self-defence," he said.

"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."

The statement comes as South Korea begins its annual summer defence drills involving thousands of civilians and troops.

Australian Associated Press