North Korea is offering negotiations with the United States in order to buy time to develop its nuclear weapons, the incoming U.S. national security adviser said Sunday.

John Bolton, a former ambassador who was tapped by U.S. President Donald Trump last week, gave the assessment as the American leader prepares to meet with North Korean dictator Kim Jong-un to discuss the regime's denuclearization.

"I think we have to look at what North Korea's motivation is here," Bolton said in an interview on the "Cats Roundtable" radio show. "I think they're very worried that they've got a different president in the White House than Barack Obama. They're worried about the pressure that the president's already put on."

Bolton is known as one of the most hawkish voices in U.S. foreign policy and has recently argued for a preventive strike on the North.

Trump picked Bolton as his national security adviser shortly after he replaced Secretary of State Rex Tillerson with another hawk, Central Intelligence Agency Director Mike Pompeo. Both decisions came after the U.S. president accepted Kim's invitation to a summit, which he said would take place before the end of May.

Moon-Kim summit to be held April 27 2018-03-29 14:48  |  North Korea
"They've got a fairly limited number of things they need to do in North Korea to make their nuclear warheads actually deliverable on targets in the United States," Bolton said. "So they want to try and slow roll the negotiations to buy more time. This is something they've done consistently over the last 25 years."

Taking months to prepare for the meeting would "simply play into the North Korean playbook," according to Bolton.

"I think the sooner we have the meeting and have a very straightforward discussion -- Is North Korea going to give up its nuclear weapons? How are we going to do it? How are we going to take it out of the country? -- not a theoretical discussion about these issues but very concretely, how they're going to denuclearize North Korea -- the sooner we get to it, cut to the chase, the better," he said.

The incoming adviser is set to take over from H.R. McMaster on April 9. (Yonhap)