The U.S. calculated last month that up to 60 nuclear weapons are now controlled by North Korean leader Kim Jong Un.
North Korea has successfully produced a miniaturized nuclear warhead that can fit inside its missiles, crossing a key threshold on the path to becoming a full-fledged nuclear power, U.S. intelligence officials have concluded in a confidential assessment.
Determining the precise makeup of North Korea’s nuclear arsenal has long been a difficult challenge for intelligence professionals because of the regime’s culture of extreme secrecy and insularity.
The country’s weapons scientists have conducted five nuclear tests since 2006, the latest being a 20- to 30-kiloton detonation on Sept. 9, 2016, that produced a blast estimated to be up to twice that of the bomb dropped on Hiroshima, Japan, in 1945.
Siegfried Hecker, director emeritus of the Los Alamos National Laboratory and the last known U.S. official to personally inspect North Korea’s nuclear facilities, has calculated the size of North Korea’s arsenal at no more than 20 to 25 bombs.
Hecker warned of potential risks that can come from making Kim into a bigger menace than he actually is.
Why build ICBMs?
Intercontinental ballistic missiles are seen as the last word in power projection because they allow a country to wield massive firepower against an opponent on the other side of the planet.
The only real reason to spend the money, time and effort building them is to fire nuclear weapons.
During the Cold War, Russia and the United States sought different ways to protect and deliver their missiles, which were hidden in silos, piggybacked on huge trucks or carried by submarines.
All ICBMs are designed along similar lines.
They are multi-stage rockets powered by solid or liquid fuel, and carry their weapon payload out of the atmosphere into space.
The weapon payload – usually a thermonuclear bomb – then re-enters the atmosphere and detonates either above or directly on top of its target.
Some ICBMs have a “multiple independently targetable reentry vehicle”, or Mirv.
This has multiple warheads and decoys, allowing it to strike multiple targets and confuse missile defence systems.
In the Cold War period, the range and potential threat of ICBMs were seen as key to the concept of “Mutually Assured Destruction” or MAD.
MAD supposedly helped maintain peace because neither side could “win” without suffering incalculable damage.
The North’s missile milestones
North Korea’s own missile programme began with Scuds, with its first batch reportedly coming via Egypt in 1976.
By 1984 it was building its own versions called Hwasongs.
These missiles have an estimated maximum range of about 1,000km, and carry conventional, chemical and possibly biological warheads.
From the Hwasong came the Nodong design – effectively an upscaled Hwasong / Scud with an extended range of 1,300km.
In an April 2016 analysis, the International Institute for Strategic Studies said the missiles were a “proven system which can hit all of South Korea and much of Japan”.
More capable missiles followed with the development of the Musudan range, which was most recently tested in 2016.
Estimates differ dramatically on its how far it can fly, with Israeli intelligence putting it at 2,500km and the US Missile Defense Agency estimating about 3,200km.
Other sources suggest a possible 4,000km.
Another development came in August 2016 when North Korea announced it had tested a submarine based “surface-to-surface, medium-to-long-range ballistic missile”, called the Pukguksong.
North Korea’s 4 July claimed test of an intercontinental ballistic missile means that Pyongyang moves a step closer to threatening the US mainland with a nuclear warhead.