Asked how quickly he believes North Korea will turn over its arsenal, Bolton told CBS he believes Secretary of State Mike Pompeo will be in discussions with North Koreans in the near future about "really how to dismantle all of their WMD and ballistic missile programs in a year".
"The officials' assessments stand in stark contrast to that of US President Donald Trump, who declared following the June 12 summit with Kim that there is no longer a nuclear threat" from North Korea.
"North Korea remains free to manufacture more nuclear weapons, ballistic missiles and other weapons of mass destruction - even though it has unilaterally frozen testing of its nuclear weapons and certain ballistic missiles", he said.
"There are lots of things that we know that North Korea has tried to hide from us for a long time", one USA official said.
He said the one-year program the USA is proposing would cover all of the North's chemical and biological weapons, nuclear programs and ballistic missiles.
Bolton said the U.S.is "going to try to proceed to implement what the two leaders agreed to in Singapore" and added that a public back-and-forth over the progress of talks is unhelpful in negotiations.
South Korea media reported on Sunday that USA envoy Sung Kim, the American ambassador to the Philippines, met with North Korean officials at the border on Sunday to coordinate an agenda for Pompeo's next visit to North Korea.
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Trump's words reversed his declaration upon his return from Singapore that North Korea had ended its nuclear ambitons. Trump touted the agreement as a significant step toward peace in the world.
Bolton added that it would be to the North's advantage to cooperate to see sanctions lifted quickly and aid from South Korea and Japan start to flow. -North Korean diplomacy prior to the Singapore summit.
"I'm confident what (Trump) intended there was, 'we did reduce the threat, '" Pompeo told a Senate panel. The Financial Times reported that Pompeo was due to visit North Korea this week but Reuters has not been able to confirm his travel plans.
"So we gave nothing".
A United States official told The Associated Press that the Post's report was accurate and that the assessment reflected the consistent view across USA government agencies for the past several weeks.
"Because Kim Jong Un has so far avoided making a commitment to halt research and development activities, the changes [at Yongbyon] are not a success or failure of the diplomatic process, but simply a signal that North Korea's nuclear infrastructure remains fully in use", Adam Mount, a director at the Federation of American Scientists, told CNN.