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Just hours before the sixth nuclear test North Korea is suspected to have conducted, the state news agency released photographs of Kim Jong-un inspecting a nuclear warhead. Defence expert Melissa Hanham decodes what information the picture could yield.

This appears to be the biggest and most successful nuclear test by North Korea to date. Initial estimates by the USGS that it reached magnitude 6.3, which would make it an order of magnitude greater than we have ever seen before.

It is probably no coincidence that on the same day North Korean state media outlet KCNA released photographs of Kim Jong-un inspecting a so-called H-bomb, or a thermonuclear warhead, just hours before.

There is no way of telling if this is the actual device that was exploded in the tunnel - it could even be a model - but the messaging is clear. They want to demonstrate that they know what makes a credible nuclear warhead.

Kim Jong-un is standing very close to the apparent warhead, dangerously close many might reasonably posit. However, it could very well be that this is simply a model of the nuclear warhead. Nevertheless it is an extraordinary bit of messaging. In March 2016 he stood very close to a missile set to be launched. He has even been photographed smoking cigarettes next to the solid fuel motors of missiles, so he is not averse to showing extraordinary risk.

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Even if it is a model, there are enough signals in this model to make it look very credible and that is to do with its shape, size and how much detail they have showed.

Typically when we've seen pictures of warheads from the US and Russia in the past they've just been cones. Here the North Koreans have shown us quite significant detail.

The bulbous peanut shaped object is an order of detail that we haven't seen before. This is the warhead itself.

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The larger side, closer to the silver cylinder with the wires protruding is probably the fission device. When that explodes it will then detonate the smaller end of the object - which is the fusion part of the explosion.

The cylinder at the back is the firing set: this is the power, the electronics that will start off the explosion.

They are showing off the nuclear warhead alongside a missile. In some of the photographs we see a tall tan-coloured cone with a yellow and black painted tip. That is the Hwasong-14 ICBM nose cone. This nose cone would be what is appended to the Hwasong-14 intercontinental ballistic missile, that was tested in July, and signalled that North Korea may just have made a significant leap in weapons development.

There is even a chart in the background detailing how it will work. In Korean, the chart seems to detail that this device is intended to fit into the cone.

The North Koreans are also showing us more detail than is required because this is a propaganda piece for outside consumption.

Melissa Hanham is a Senior Research Associate at the Middlebury Institute of International Studies at Monterey.