North Korea wants an H-bomb but experts doubt it tested one

North Korea's government bragged Wednesdaythat it hadtested "a smaller H-bomb," calling it the "H-bomb of justice."

White House spokesman Josh Earnest, however, counters that initial analysis"is not consistent with the North Korean claims of a successful hydrogen-bomb test."

Earnest did describe the blastas a nuclear test, making the one this week North Korea'sfourth. And MelissaHanham, a Canadian expert on North Korea with the James Martin Center for Nonproliferation Studies in Monterey, Calif., told CBC News that it was "pretty much universally acknowledged it was a nuclear test, but there's a lot of skepticism about whether it was anH-bombtest."

The South Korean military also doubts it was an H-bomb test, according the South Korea's Yonhap news agency.

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Hanham says when, and if, radionuclide data from the explosion becomes available, experts should have a pretty good idea of just what kind of explosion it was. That could take anywhere from two weeks to two months.

While Hanham says an H-bomb explosion "is a much more complicated kind of explosion to execute," McMaster University physicistCliff Burgessnotes H-bomb technology is "similar to what they're mastering with the atomic bomb."

He's not saying the technological leap is trivial, but points out that the North Korean weapons designers would be working on technical issues similar to those involved with thedevelopment of their atomic bomb.

A-bombs versusH-bombs

There are some key differences between atomic bombs and hydrogen bombs. In basic terms:

• An A-bomb relies on fission, the splitting of atoms.
• AnH-bomb relies on fusion, which produces energy through combining light atoms to make heavier ones.
• A fission bomb uses an ordinary explosion to bring together enough uranium or plutonium to create a critical mass, which causes a much, much bigger explosion.
• A fusion bomb uses a fission explosion to compress hydrogen, making it very dense and hot, so that the hydrogen atoms fuse rather than fly apart, also causing a much larger explosion.

Burgess says that all the big nuclear powers developed hydrogen bombs, "partly because it's do-able once you've got the infrastructure to make the atomic bomb."

Assessing North Korea's test claims are complicated by the fact that whilea fully developedH-bombis more complexthan a basic atomic bomb, there are variations of atomic bombs thatincorporate hydrogen.

"Ready to detonate an H-bomb'

In December, North Korean leader Kim Jong-un described his country as, "a powerful nuclear weapons state ready to detonate self-reliant A-bomb and H-bomb."

That month, while writing that his own government considered Kim's statement a bluff, Konstantin Asmolov, anexpert on Korea at the Russian Academy of Sciences, wrote that "the term 'H-bomb'implies a range of weapons, some of which are rather basic, and well within the current level of North Korean technical and scientific development."

Asmolov's point is that a nuclear weapon can still be considered an H-bomb, even if it doesn't use an ordinary nuclear weapon to ignite a hydrogen fusion reaction and a much bigger explosion.

What's called a boosted fission weapon could technically fit the definition of an H-bombsince ituses hydrogen to speed up the fission reaction. This produces a bigger explosion,although nowhere near as big as afully developedH-bomb.

To put this in context, the unit for measuringH-bomb explosions the megatonisa thousand times bigger than the kiloton unit used to measure A-bomb and boosted fission weaponexplosions.

According to the Comprehensive Nuclear-Test-Ban Treaty Organization, this week's explosion in North Korea measured "essentially the same" as a nuclear test conducted at the same location in 2013, thePunggye-ri Nuclear Test Facility, in mountainous terrain in the northeast of the country.

Hanham's reasons it wasn't an H-bomb test

North Korea's statement describesitsH-bombtest as a "spectacular success" butHanham saysshe doubts Wednesday's blast in North Koreacouldhave been a fullH-bomb test.

The explosion wasn't big enough, according to the seismic data. A good thing, too, she says, since the Punggye-ri testsite couldn't have contained the explosion if it was a real H-bomb, nor is she aware of evidence the countryhad prepared the site for such a test.

The U.S. and Russia do have relatively smallH-bombsin their nuclear arsenals, but developing those weapons is more technically challenging than buildinga bigH-bomb. The superpowers developed their big bombsmuch earlier than the smaller, tactical weapons.

Hanhamhypothesizes that the country definitely wants to have anH-bomb, but it isprobablyexperimenting with some kind of boosted nucleardevice. However, she does note the slight possibility that it was a failed test in which only the fission reaction went off, without initiating the fusion reaction.

Hanham adds that as far as her research has determined, there aren't theindicators thatNorth Korea hasreacheda point in its technologicaldevelopment where it could detonate a fullH-bomb. But if the radionuclide data does indicate that North Korea conducteda boosted atomictest, Hanham says that will mean North Korea has advanced its nuclear program, and that "they're further down the line" towards achieving their goal of developing a real H-bomb.

Shepoints out that, "For North Korea, these tests aren't just scientific tests, in many ways they're political tests and they are meant to give a signal to the outside world, and also to appear strong to their domestic audience."

Which may be why North Korea's official statement about the test contains this verbal flourish,"Nothing is more foolish than dropping a hunting gun before herds of ferocious wolves."

Video produced in December 2015 by the James Martin Center for Nonproliferation Studies.