The site was used for each of its six underground nuclear test explosions. The dismantling would come before North Korean leader Kim Jong Un and U.S. President Donald Trump meet for June 12 talks in Singapore expected to focus on Kim's nuclear program.
The U.S.is said to consider North Korea's declaration of halting further nuclear and missile tests as "not enough" for a "complete, verifiable, irreversible dismantlement", Yonhap said.
North Korea's official name is the Democratic People's Republic of Korea.
"In the end, North Korea will remain a nuclear power packaged as a non-nuclear state", he added. "It will be American know-how, knowledge entrepreneurs and risk takers working alongside the North Korean people to create a robust economy".
United States ambassador Robert Wood meanwhile told the same forum that his country "welcomes the professed commitment by North Korea to end nuclear tests and missile launches and the shut-down of its nuclear test site". Analysts say that while the closure of the site is important, it doesn't represent a material step toward full denuclearization.
Pompeo - who recently returned from another set of meetings with North Korean leader Kim Jong-un - said the benefits North Korea can gain by scrapping its nuclear ambitions should be obvious.
'We have two more tunnels that are bigger than the existing ones and that they are in good condition, ' he said.
The move is another notable step in North Korea's diplomatic charm offensive, which comes after a year of constant weapons testing and heated rhetoric between Washington and Pyongyang.
"DPRK will join global desires and efforts for a total ban on nuclear tests", North Korea's ambassador to the United Nations in Geneva Han Tae-song said in an address to the Conference on Disarmament, using North Korea's official acronym. In June 2008, worldwide broadcasters were allowed to show the demolishing of a cooling tower at the Nyongbyon reactor site, a year after the North reached an agreement with the US and four other nations to disable its nuclear facilities in return for an aid package worth about $400 million.
Bolton has previously made hawkish public comments that supported preemptive U.S. attacks on North Korea to counteract the threat of their nuclear arsenal.
A senior North Korean defector on Monday said North Korean leader Kim Jong-un's ultimate goal remains to become a nuclear-armed state.
Regardless of what sort of deal Trump and Kim will try to reach during their summit, American officials are adhering to the position that they will not allow a repeat of North Korea pledging denuclearization and then reneging on those pledges as in the past.