US officials say North Korea has continued to enrich uranium and is trying to deceive the US to win concessions.

US intelligence agencies believe North Korea has increased production of fuel for nuclear weapons in recent months and that North Korean leader Kim Jong-un is trying to deceive the US in order to extract more concessions, NBC News has reported.

Citing more than a dozen US officials who were familiar with the intelligence assessment, NBC News Saturday reported they disagreed with US President Donald Trump‘s sentiment that the nuclear threat from North Korea has decreased since he had met Kim.

The officials believe Pyongyang is holding on to its nuclear weapons which “it believes are essential to survival” while “positioning itself to extract every concession it can from the Trump administration”, NBC reported.

The latest intelligence assessment reportedly showed that North Korea had upped uranium enrichment while engaging in diplomacy with the US.

One US official told NBC that “there’s no evidence that [North Korea] are decreasing stockpiles, or that they have stopped their production.

“There is absolutely unequivocal evidence that they are trying to deceive the US,” the official reportedly said – an opinion that was held by four more officials who spoke with the US network.

Officials also told NBC the latest intelligence assessment concludes there is more than one secret facility to enrich nuclear material, aside from the disclosed Yongbyon nuclear site.

The White House did not immediately respond to a request for comment, NBC reported.

The report comes days after a North Korea monitor claimed that operations were continuing and that infrastructure works were carried out at the Yongbyon site.

“Commercial satellite imagery from June 21 indicates that improvements to the infrastructure at … Yongbyon Nuclear Scientific Research Center are continuing at a rapid pace,” 38 North reported.

After meeting with Kim on June 12, Trump tweeted that “There is no longer a Nuclear Threat from North Korea”.

Just landed – a long trip, but everybody can now feel much safer than the day I took office. There is no longer a Nuclear Threat from North Korea. Meeting with Kim Jong Un was an interesting and very positive experience. North Korea has great potential for the future! — Donald J. Trump (@realDonaldTrump) June 13, 2018

The highly-anticipated summit ended in the signing of a joint statement in which North Korea pledged to work towards complete denuclearisation of the Korean Peninsula.

The agreement was criticised for failing to include new commitments on the part of Pyongyang with regards to its nuclear programme and for lacking substance.

Meanwhile Trump at a press conference announced he would order and end to joint military exercises with South Korea, which has been viewed as a major concession on the part of the US.

Last week, Trump said a process of “total denuclearisation … has already started” in North Korea while US officials familiar with intelligence told Reuters news agency there was no evidence of new moves to dismantle sites since the summit.

Ahead of the summit, North Korea suspended its nuclear and missile tests.

In May, North Korea demolished its aged but only nuclear test site at Punggye-ri – where it had staged six atomic tests – in a show of goodwill before the summit.

US Secretary of State Mike Pompeo last week said he would go back to Pyongyang “before too terribly long” to follow up on the agreement reached during the talks.