What is an ICBM? A guide to North Korea and Kim Jong-un’s nuclear weapons

We break down what we know about Kim Jong-un's nuclear weapon tests and missiles

Emergency alarms rang out across Japan overnight as North Korea fired another ballistic missile over the country.

The test took place less than a fortnight after Kim Jong-un reportedly tested a hydrogen bomb in Kilju County, the site of North Korea's nuclear test site. North Korea’s latest missile is said to have reached an altitude of 478 miles (about 770km) and was airborne for around 2,230 miles (3,700km). It eventually landed in the sea near Hokkaido, according to South Korea's military.

South Korea has since responded by firing two ballistic missiles into the sea in a simulated strike on its northern neighbour.

The US condemned the test and is calling on China and Russia to step up their efforts to help contain the problem and put pressure on North Korea’s leader. The UN Security Council is due to meet later today at the request of America and Japan.

In response to Kim Jong-un's hydrogen bomb test last month, the US warned that any threat would be met with a "massive military response", while South Korea has carried out its own tests using with both ground- and air-launched rockets. There are also rumours North Korea has been moving what appears to be an intercontinental ballistic missile, ICBM, towards its west coast.

The claims come from an unidentified intelligence source and have been unverified, but moving an ICBM to the west of North Korea would escalate tensions further as it puts it closer to the US. In particular, the claims say the ICBM could now be situated on Sohae Satellite Launching Station, a major ICBM testing site northwest of Pyongyang. 

August's reported hydrogen bomb test marked the sixth time North Korea has trialled it nuclear weapons in recent years, the last being in September 2016. Kim Jong-un has defied calls from the UN to cease nuclear testing as well the sanctions imposed by the international body which prohibits North Korea from developing nuclear weapons testing missiles which could potentially reach the mainland US. 

Earlier in the month, North Korea threatened to launch four liquid-fuelled, intermediate-range ballistic missiles (IRBM) into the ocean near American territory Guam. Donald Trump’s promise to rain down “fire and fury” in response to those threats on Guam stoked rhetoric around a teetering conflict before North Korea escalated tensions by announcing alleged plansto fire Hwasong-12 rockets by mid-August. This did not take place as planned.

But what is the reality of North Korea’s nuclear capabilities, and what defences does the West have to stop any missiles in their tracks?

Hydrogen bombs explained

All nuclear weapons use a process called fission. It is this process that forms the catalyst needed for their staggering explosions. Some of the first nuclear weapons, developed by the US and including the Little Boy dropped on Hiroshima during the Second World War, generated fission by firing a hollow uranium-235 cylinder at a target made from the same material. These were atomic bombs. Hydrogen bombs are altogether more extreme and dangerous. 

They are effectively two bombs in one – a fission bomb and a fusion bomb. Like in an atomic bomb, the fission process releases a blast of powerful radiation. However, instead of firing this at the hollow cylinder and creating an explosion, the radiation is fired at the second 'fusion bomb' which creates an explosion so powerful, it forces atoms to crash into each other and merge. The energy from this event triggers a bigger blast than the one produced by an atomic bomb. Some experts say these blasts are up to 1,000 times more powerful. 

What nuclear weapons does North Korea have?

Reports suggest that Kim Jong-un does have some form of nuclear bomb, but there is disagreement over whether the country has managed to make warheads small enough to fit on its missiles. For months, the belief was that North Korea was overplaying its ability to successfully "miniaturise" nuclear warheads, but a recently leaked report in the The Washington Post points to evidence the nation has an estimated 30 to 60 nuclear warheads.

If a hydrogen bomb has been tested, this bomb could either be the one Kim Jong-un intends to fit onto a weapon, or is a prototype for a future version.

“The IC [intelligence community] assesses North Korea has produced nuclear weapons for ballistic missile delivery, to include delivery by [Intercontinental Ballistic Missiles] ICBM-class missiles,” states the assessment, written by US intelligence officials.

What is an intermediate-range ballistic missile?

A missile is a guided weapon, unlike a rocket, and a ballistic missile is one that can move along a suborbital trajectory, skimming the Earth’s atmosphere to travel much further than normal missiles. North Korea has specifically threatened to fire its Hwasong-12 weapons, which are domestically developed intermediate-range ballistic missiles.

Reports about the only successful Hwasong-12 test, in May 2017, suggest the weapon travelled about 700km (430 miles) before falling into the Sea of Japan. Analysts believe the same missile could reach a maximum range of around 4,500 km (2,796 miles) if fired at a lower maximum altitude (apogee).

(Above: What analysts believe to be a Hwasong-12 missile, Credit: Wong Maye-E / AP)

Source: http://www.alphr.com

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