US President Donald Trump's National Security Adviser John Bolton says North Korea has not lived up to its end of the Singapore agreement on denuclearization.

Axar.az reports citing The Washington Post.

“What we really need is not more rhetoric,” Bolton said in an interview on Fox News on Tuesday. “What we need is performance from North Korea on denuclearization.”

Following their summit in Singapore in June, Trump said North Korean leader Kim Jong-un had promised to immediately start working to end Pyongyang’s weapons programs.

North Korean state media has since highlighted steps the country has taken, including a moratorium on nuclear and missile tests, the dismantling of a nuclear site, and the return of the remains of American soldiers killed in the 1950-53 Korean War.

Pyongyang has urged Washington to take reciprocal measures including officially declaring an end to the war and removing sanctions.

However, Bolton said the United States has lived up to the joint declaration that was issued after the June 12 summit between Trump and Kim.

“It’s just North Korea that has not taken the steps we feel are necessary to denuclearize,” he said, adding that dropping sanctions was not currently on the table.

The comment came as The Washington Post reported that US officials believe North Korea could be in the process of building new intercontinental ballistic missiles.

Bolton said that Secretary of State Mike Pompeo was ready to return to North Korea for another meeting with Kim. He also said that Trump "is prepared to meet at any point."