On Sunday, Bolton declined to comment on USA intelligence assessments, but said the administration is "very well aware of North Korea's patterns of behavior over decades of negotiating with the United States".
Trump made the declaration after his June summit with North Korean leader Kim Jong-un, during which the President promised Kim to stop the "war games" by ending US military exercises with South Korea.
China and the United States both hope to see the Korean peninsula free of nuclear weapons.
Japanese defense ministry officials were not available for immediate comment.
Xi in turn told Kim he "actively supports North Korea's reform and opening-up and will proactively cooperate with issues associated with the efforts", according to the Yomiuri.
Put another way, the regime may have suspended its missile and nuclear tests, and made a big show of dismantling its one known test site, but there continues to be no reason to believe North Korea has any intention of denuclearizing, or any indication that they are doing anything other than posturing in an attempt to gain additional concessions from the Trump administration.
The assessment contradicts US President Donald Trump's remarks that "there is no longer a nuclear threat from North Korea", following a landmark summit with the North's leader Kim Jong-un on June 12 in Singapore.
The report stated that North Korea has "at least one undeclared facility to enrich nuclear fuel" besides Yongbyon, the main nuclear location.
When asked what would happen if North Korea does not follow through with promises of denuclearization, Trump said: "I don't want to be threatening...you've seen what was perhaps going to happen".
"I'm confident what (Trump) intended there was, 'we did reduce the threat, '" Pompeo told a Senate panel.
He said Secretary of State Mike Pompeo will likely discuss that proposal with the North Koreans soon.
As of now, there is little proof that North Korea intends to go down that road, longtime North Korea observers say.
Bolton also said on "Face the Nation" that during the US-North Korea summit in Singapore, Kim was "very emphatic several times" about turning over the arsenal, which was a change from previous regimes.
Bolton said the US has developed a program that would enable a relatively rapid dismantlement of North Korea's arsenal if the Kim regime is cooperative.
"I think they're very serious about it", the President responded.
"Work is ongoing to deceive us on the number of facilities, the number of weapons, the number of missiles", an official said.
Specifically, the DIA has concluded that North Korean officials are exploring ways to deceive Washington about the number of nuclear warheads, and missiles and the types and numbers of facilities they have, believing that the United States is not aware of the full range of their activities.
Such inspection trips have raised the prospect of Pyongyang seeking to enhance cross-border economic cooperation with China, experts said, as Beijing appears to be seeking easing of its enforcement of sanctions on North Korea.