NORTH Korea has been making rapid improvements to its nuclear research facility — despite Kim Jong-un’s pledge to denuclearise during his summit with President Donald Trump, the New York Post reports.

The dictator promised to “work toward” the goal at the June 12 summit with President Trump in Singapore, which produced a vaguely worded agreement that provided few details about the rogue regime’s commitment.

Mr Trump — who declared on Twitter that there was “no longer a Nuclear Threat from North Korea” — claimed the process would start quickly, saying “it will be a total denuclearisation, which is already taking place.”

Jenny Town, managing editor of respected website 38 North, wrote on Twitter: “Infrastructure improvements continue at Yongbyon. Underscores reason why an actual deal is necessary, not just a statement of lofty goals.”

Recent satellite imagery showed that not only were operations continuing at present at the Yongbyon nuclear site, the North also was carrying out infrastructure works, according to 38 North.

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

The cooling system for the plutonium production reactor has been modified and at least two buildings have been built on the site, possibly for use by visiting officials, according to The Guardian.

A new engineering office building also has been completed and construction has continued on support facilities at the complex, according to a blog post written by Frank Pabian, Joseph Bermudez Jr. and Jack Liu.

But continued operations at the site “should not be seen as having any relationship with North Korea’s pledge to denuclearise,” the monitor noted, adding that nuclear officials could be “expected to proceed with business as usual until specific orders are issued from Pyongyang.”

Meanwhile, the Trump administration last week extended decade-old sanctions against Kim’s regimen, citing the “extraordinary threat” from the North’s nuclear arsenal.

After the summit, Mr Trump also abruptly announced a halt to joint military drills with South Korea, calling the exercises “provocative” to the North and “very expensive.”

It took the Pentagon several hours to confirm the surprise decision, and the drills were only officially cancelled two weeks after the summit.

Defence Secretary James Mattis is set to visit Seoul on Thursday to discuss the issue with his South Korean counterpart.