According to announcements made Monday by the Korean Central News Agency (KCNA) the North Korean government’s official mouth-piece, scientists there had detonated a half kiloton device in an under ground testing site deep in the country’s northern mountain range. KCNA also reported there had been no radiation leakages as a result of the test.

But this fact has nuclear experts scratching their heads, as even the most modest of underground nuclear tests yield some radioactive fallout, an anonymous US Official told the Washington Post.

A ‘responsible’ member of the nuclear club
The official therefore suggested that the KCNA might have reported that there had been no leakage as an effort to mollify North Korea’s neighbours’ fears of possible radioactive contamination and show that it was a responsible new member of the Nuclear Club.

This would be an obvious whitewash statement, as, sooner or later, at least some radiation would register internationally. But according to the Post, so far none has – though the official did acknowledge that it could sometimes take several days for monitoring devices to pick up the radiological evidence of an underground test.

South Korea also said that it wasn’t certain that the North’s test was a success and that resolving that doubt would take about two weeks, the London Guardian reported.

Nonetheless, the evidence so far suggests that Russia’s estimates that North Korea has set of a device measuring from five to 15 kilotons in strength are far too high.

Did Pyongyang just blow up dynamite?
The vibrations registered by seismologists worldwide corresponded to an explosion in the Korean Peninsula are equivalent to some 500 tons of TNT – leading some experts to question whether or not the North Koreans did, in fact, simply explode a conventional dynamite-driven device and announce it as a nuclear detonation to perpetrate a global fake-out that would garner it more diplomatic respect.

According to Post, North Korea had phoned Chinese authorities 20 minutes before the test and notified them they would be testing a four-kiloton device. Yet the yield that was reported by the KCNA was only a half a kiloton – far from the 15-kilotons that were dropped on Hiroshima and the 23-kiloton device that fell two days later on Nagasaki.

"For an initial test, a yield of several kilotons has been historically observed,” the official told the Post.

Isolated North Korean scientists could have misread the directions
Some officials interviewed by the Post said that Korea could have been counting on a four-megaton blast. But the scientists, who had been working for years in isolation, could simply have gotten some of the details wrong.

The Post reported that intelligence officials were looking at four possibilities to explain the size of the blast, the most likely of which appeared to be that only a fraction of the device’s core exploded. If that were the case, the test would still be considered successful, officials said, because some plutonium was exploded. But it may also lead the North Koreans to conduct additional tests to determine what went wrong.

It is also possible, two other analysts told the Post, that Pyongyang used less plutonium because it has less stockpiled than US intelligence believed.

"A low yield can be a failure in design or it can be bad luck," said Michael Levi, a nuclear expert at the Council on Foreign Relations told the Post.

While evidence suggests that North Korea got help from rogue Pakistani nuclear scientist Abdul Qadeer Khan in developing its nuclear programme, the isolated, Stalinist country would also have had to figure out a lot of technical bomb-making details itself – another likely factor in a possible failed test, said Vladimir Orlov of the PIR Center, a Moscow –based nonproliferation think-tank, the Guardian reported.

“Both intellectually, technologically and financially, they are really in practical isolation, which is relatively good news,” Orlov told the Guardian. He added that the apparent low yield “indicates that the North Koreans really have trouble making what ordinary people would call a nuclear bomb, they really have a primitive nuclear device.”