North Korea Unveils a Miniaturized Nuclear Warhead for KN08 Missiles

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North Korean leader Kim Jong Un inspects a miniaturized nuclear warhead designed for ballistic missiles. Un stands in front of a KN08 ballistic missile, that is likely to carry the new, thermo-nuclear warhead, The undated photo was released today by the North Korean Central News Agency (KCNA).
The tip of the KN-08 missile carries a tri-conical reentry vehicle, containing the warhead. This section weighing 700-1000 kg is likely to carry a miniaturized nuclear device,
The tip of the KN-08 missile carries a tri-conical reentry vehicle, containing the warhead. This section weighing 700-1000 kg is likely to carry a miniaturized nuclear device. The diameter of the nose cone, estimated to be 1.25 meters in its base (4 ft) fits well with the diameter of the warhead, likely to be less than one meter in diameter.

North Korea claims it has the know how and capability to develop a nuclear warhead to equip ballistic missiles. This claim has been substantiated today, by the leader of the Democratic People’s Republic of Korea (DPRK), Kim Jong-Un, presenting a complex spherical object claimed to be the country’s miniaturized thermonuclear warhead.“The nuclear warheads have been standardised to be fit for ballistic missiles by miniaturising them,” Kim noted during a visit with nuclear technicians that was reported by the DPRK state media today.

It is possible that the new warhead is designed for the Korean KN08 intermediate range ballistic missile that has yet to be tested in flight. Once proven, the missile is expected to boast the range and payload capacity to deliver attacks on US targets in the Pacific and west coast. Kim also stressed that the miniaturised warheads were “thermo-nuclear” devices, echoing the North’s claim that the nuclear test it conducted in January was of a more powerful hydrogen bomb.

This is the first time Kim has directly claimed the breakthrough that experts see as a game-changing step towards a credible North Korean nuclear threat to the US mainland.

His comments came a day after the North’s powerful National Defence Commission threatened pre-emptive nuclear attacks on South Korea and the US mainland, as Seoul and Washington kicked off large-scale joint military exercises.

Military tensions have surged in the region since the North carried out its fourth nuclear test in January and a long-range rocket launch last month.

Schematic view of a nuclear fission device.
Schematic view of a nuclear fission weapon.
“His comments and the photos are making the message very explicit: ‘We have a nuclear weapon and you have to respect us’,” Melissa Hanham, another expert on North Korea’s weapons program at MIIS, James Martin Center for Nonproliferation Studies of the Middlebury Institute of International Studies (MIIS) in California.

North Korea’s claim to have successfully tested an H-bomb in January was greeted with scepticism at the time as the estimated yield was seen as far too low for a full-fledged thermo-nuclear device.

However, weapons experts have suggested it may have been a “boosted” fission device, which makes more efficient use of nuclear material and can be made smaller without sacrificing yield.

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[ismember]The newly unveiled warhead could possibly fit into this nose cone section, seated in a Reentry Vehicle (RV) that protects the sensitive and complex fission device complex from the pressures and heat loads associated with re-entry into the atmosphere. Such complex (RV plus warhead) would weigh about 1,000 kg (2,200 lb) and, therefore, fits only missiles that can lift such payloads to a low earth orbit. North Korean long range missiles have yet to achieve the capability to lift such payloads. While the short range missiles (1,300 – 2,000km) can lift one tonn class warheads, their larger missiles, such as the Kwangmyongsong-4 satellite launcher used in the February 2016 test launch could carry a mass of 200 kilograms (440 lb).[/ismember]

North Korean nuclear fission warhead displayed to leader Kim Jong Un. [ismember]The design shows the outer layer containing multiple detonators using lense shaped charges, activated simultaneously to cause an 'implosion' that triggers the plutonium core into chain reaction. Implosion devices are more efficient than the gun type and do not require high-grade uranium, but they are more complex in their design and more delicate, requiring precise coordination of the timing for the detonation of the surrounding explosive charges.[/ismember] Photo: KCNA.
North Korean nuclear fission warhead displayed to leader Kim Jong Un. [ismember]The design shows the outer layer containing multiple detonators using lense shaped charges, activated simultaneously to cause an ‘implosion’ that triggers the plutonium core into chain reaction. Implosion devices are more efficient than the gun type and do not require high-grade uranium, but they are more complex in their design and more delicate, requiring precise coordination of the timing for the detonation of the surrounding explosive charges. The spherical object seems to be less than one meter in diameter (3.2 ft), designed to fit into the KN08 nose cone. The warhead shows multiple (redundant) connector cables distributing the synchronized activation of explosive lenses, and an object likely being part of the ‘pit’ used for safe, arm and mechanisms.[/ismember] Photo: KCNA.