The North Korean foreign minister told the UN that US threats against his country make the visit of his rockets "inevitable".
North Korea's foreign minister, Ri Yong Ho, harshly attacked President Donald Trump on Saturday, calling him "a mental derangement that is full of megalomania".
The American people themselves believe that Donald Trump is an "evil commander," a "lying king," the North Korean foreign minister said in his address to the UN General Assembly.
Their threats to "completely destroy" North Korea make "the visit of our rockets inevitable", Ri said.
"In the event that lives are lost in the United States it will be his fault, because of that suicide mission of Trump", said the chancellor.
"North Korea is a responsible nuclear state," but "we will take necessary and relentless preventive measures ... if the United States and its vassals want to carry out" attacks against the country, he said.
Ri also said that the "barbaric and odious" sanctions imposed by Washington will not change Pyongyang's mind.
"We are now only a few steps from completing our nuclear capacity, it is absurd to think that our country is going to deviate a millimeter of its course by as strict as the sanctions that impose us", said the chancellor of North Korea.
In his first address to the UN General Assembly on Tuesday, Trump threatened to "totally destroy" North Korea, naming North Korean leader Kim Yong-un as a "rocket man" on a "suicide mission."
Kim shot Trump in turn on Thursday: described him as "mentally upset" and warned that he "will pay dearly" for his threat.
In recent weeks North Korea has detonated its sixth nuclear bomb and tested intercontinental missiles, saying it must defend itself against hostilities from the United States and its allies.
An earthquake detected on Saturday in North Korea is probably a replica of Pyongyang's September 3 nuclear test, Lassina Zerbo, head of the Comprehensive Nuclear-Test-Ban Treaty Organization (OTPC), told AFP.
US bombers flew near the east coast of North Korea on Saturday in a show of strength of US military power over the Pyongjang weapons program, the Pentagon reported.