North Korea's public display of detonating its underground nuclear test tunnels last month may have been a superficial spectacle done for propaganda reasons rather than a real move toward denuclearization, according to U.S. intelligence and international arms control experts.

"The fact that journalists were reportedly only around 500 meters from the explosions is a good indication that these were small blasts, and the amount of dust leads us to believe that they were quite superficial," an international arms official who follows North Korean actions told CNN.

The experts added that the "explosions seem to have been too small" for scientists to tell if tunnels were really collapsed.

International journalists were invited in to watch the detonation of test tunnels at Punggye-ri, including a CNN crew, who was among the two dozen journalists invited to watch detonations at three tunnels. They observed the explosions from just 500 meters, or 547 yards away.

However, weapons inspectors or nonproliferation experts were invited to the demolitions, and now believe they were just put on for show, a finding U.S. intelligence underscores, notes CNN.

Hours after journalists observed the explosions, President Donald Trump and the White House announced that a planned summit between himself and North Korea's leader was canceled. The president said Friday the June 12 summit is on again, even though Pyongyang has not made any more good-will demonstrations.

Portions of the tunnel complex also appeared to remain usable, based on seismic sensors in the region.

Imagery also showed that technical equipment had been removed from the tunnel complex before the detonations, meaning North Korea could be keeping it for future use.

CNN reported this week that according to intelligence assessments, Kim may be keeping the capability to regenerate his nuclear program, even if he does give up warheads and missiles during the upcoming negotiations.

"He is not going to do anything that allows him to become vulnerable," an official told CNN.