The regime is only known to have produced an atomic bomb so far.

But what exactly is the difference between the two, and how likely is it that North Korea

has produced an H-bomb? Kwon Jang-Ho explains.

Atomic bombs, or A-bombs, are also known as fission bombs, as they use a nuclear fission

chain reaction to set off the explosion. Enriched pieces of uranium or plutonium are

smashed together, in order to release huge amounts of energy.

Hydrogen bombs, or thermonuclear weapons, are also know as fusion bombs, because they

require a fusion reaction between hydrogen isotopes.

But a fusion reaction requires an enormous amount of energy to trigger it.

That energy produced from an A-bomb. So in essence, an H-bomb requires an A-bomb

inside it to set it off. The Hiroshima A-bomb dropped on Japan in 1945

was recorded to have released about 15 kilotons in energy and carried a blast radius of 1.6km.

The minimum yield an H-bomb produces is 1 megaton and has a blast radius of around 30km.

There is also no limit of how big an H-bomb can be, unlike the A-bomb.

But compared to its potential power, it is said to be quite easy to develop, once an

atomic bomb has been produced.

"China first tested an atomic bomb in 1964. They tested their first H-bomb in 1967. It

only took 2 years and 8 months to develop...It's been three years since North Korea last tested

a atomic bomb, and we can safely assume that they have been trying to develop a thermonuclear

weapon."

But despite North Korea's announcement, it looks like the regime has not quite yet developed

an H-bomb.

"If you look at size of the seismic activity, there's been not much difference with their

atomic bomb tests... Just by looking at the size, we can be sure it wasn't a full H-bomb."

Kwon Jang-ho, Arirang News.