IT HAS been a record year for North Korea’s nuclear ambitions. The secretive nation tested its fifth nuclear device last month, the second test this year and the largest so far. Remote monitoring put the underground explosion at 10 to 15 kilotons, about the size of the Hiroshima bomb. Days later, it conducted its .
“The threat has now reached a dimension altogether different from what has transpired until now,” Japanese prime minister Shinzo Abe after the nuclear test. “We must thwart North Korea’s plans.”
But how? The North has several times agreed to limit its nuclear plans in return for aid or security guarantees, but these deals have always fallen apart. Now the fear is it won’t give up its nukes – unless it collapses, which could be worse.
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Before Kim Jong-un became leader in 2011, the nation’s nuclear threat seemed constrained. “It had limited fissile materials and nuclear tests,” says at Stanford University in California, and no way to launch.
Kim accelerated development (see timeline) and the country now claims it can fit nuclear warheads on missiles.
“It is very likely that North Korea has a nuclear weapon that could hit South Korea or Japan“
“It is very likely that North Korea has a nuclear weapon that could hit South Korea or Japan,” says Joe Cirincione of the Ploughshares Foundation, a US think tank. It may soon even be able to hit the continental US, making North Korea a top priority for the incoming US president.
How can we tell the North’s true capabilities, given its secrecy? While seismographs record the explosive power of a bomb, there is no way to confirm its physical size, but we do have clues.
First, we can look to history. The nation is at a significant point in its nuclear development, says at the Middlebury Institute of International Studies in Monterey, California. The US, UK, China, Russia and France had all shrunk their warheads by their fifth tests. North Korea should have made similar progress.
The nuclear material used can also hint at its size. Outside observers think the last two tests were fission bombs boosted by hydrogen isotopes. These release neutrons in a thermonuclear reaction that produces more explosive force per kilogram of fissile material, usually enriched uranium or plutonium. Satellite images confirm that a plant visited in earlier inspections, which could be used to make the required isotopes, is now finished.
The North’s early tests released radioisotopes that could be detected remotely. These showed they were plutonium devices. Hecker, who has visited North Korea’s main nuclear facility in Yongbyon, says it probably has enough plutonium for six to eight bombs and produces another bomb’s worth per year.
North Korea also has uranium. Based on satellite images and a 2010 visit to its enrichment plant, Hecker calculates that it has 400 kilograms of highly enriched uranium (HEU), 16 bombs’ worth, and can add six bombs per year.
Smaller warheads
The recent underground tests vented no material, so we don’t know what the devices were made of. But descriptions of a warhead released by the country in March suggest it is using nested shells of plutonium, HEU and hydrogen isotopes, says Lewis. “Britain used just such a design in its fifth nuclear test,” he says.
This design allows for smaller warheads, and hence more of them. at the Institute for Science and International Security in Washington DC calculates that Kim now has 12 to 20 nuclear weapons at his disposal. By 2020, North Korea could have 50 to 100, he says, and could field a crude thermonuclear weapon with a yield approaching 100 kilotons.
Who could it target? This year saw tests of conventional missiles launched from land and submarine that reached Japanese waters – and could fly further. These short-range missiles could carry warheads that weigh between 700 kilograms and a ton.
To hit the US, it needs a lighter warhead, a way to slow it down in flight and heat shields for re-entry. Photos released by North Korea in March showed tests of a heat shield and in April it showed off a stationary test of the KN-08, a copy of a Soviet intercontinental ballistic missile (ICBM). This could launch a 500 kg warhead as far as Washington DC, says of Aerospace Corporation in California. Flight tests might be only a year away.
But North Korea is unlikely to nuke the US, given the chances of a devastating response. Lewis says it only wants ICBMs to deter the US from striking first, as the mobile KN-08 would survive to retaliate.
The North is more likely to aim shorter-range weapons at the ports and airports needed to bring in US troops to defend South Korea, he says: “The goal for the leadership is survival, and if troops move in they have nothing to lose.” South Korea has missile defence, but it is only partial.
How do we stop all this? “There must be talks,” says at Columbia University in New York. “They may not work, but what we have now is guaranteed to fail.”
Talks almost worked before. “There have been several efforts that have successfully delayed North Korea’s nuclear progress,” says Albright. “But they ultimately failed.”
In 1994, North Korea and the US signed the Agreed Framework. The North pledged to give up its spent fuel, accept inspectors and stop plutonium production in return for nuclear power plants that make less plutonium. The US promised no nuclear strikes and to phase out sanctions.
“It’s the best deal we could have gotten, and we lost it,” says Lewis, as George W. Bush took a tougher line. Sanctions remained, the new power plants were delayed, and in 2002 the US accused North Korea of secretly enriching uranium. The year after, North Korea left the agreement, and the Nuclear Non-Proliferation Treaty.
Since then talks have repeatedly restarted only to be scuppered by the North’s reactions to perceived aggression, including satellite launches condemned by the UN as banned missile tests (see “Missile to the moon“).
Now the US will talk only if North Korea agrees to freeze its programme. The North refuses.
That leaves just trade sanctions to put pressure on the nation. Both Donald Trump and Hillary Clinton want to tighten these. But nearly all North Korea’s foreign business goes via China, whose enforcement of sanctions is crucial – and it is unlikely to hurt North Korea enough to force concessions, for fear the regime might collapse.
“Beijing doesn’t like a nuclear North Korea on its border,” says Lewis. “But it certainly doesn’t want a collapsed nuclear state.”
“There must be talks. They may not work, but what we have now is guaranteed to fail“
So what can be done? It might help if Pyongyang felt less threatened, an approach that helped South Africa give up its nukes in 1989. Last month, North Korea’s foreign minister said they had “no other choice but to go nuclear”, given annual US and South Korean military exercises “aimed at… the occupation of Pyongyang”.
It’s not just paranoia. South Korea uses a mock-up of Kim Jong-un’s palace for target practice, and the US has flown a nuclear-capable bomber near its border.
Confronting North Korea in this way is more likely to make a conflict go nuclear, says at the Asia Pacific Centre for Security Studies in Honolulu. Instead, the US and others should de-emphasise nukes in their deterrence, giving North Korea’s leadership greater security.
That will be impossible if South Korea or Japan get their own nuclear weapons. Domestic pressure to do that is growing, and Trump backs a nuclear Japan. Philip Jun of the Ploughshares Foundation fears that a military miscalculation – say a North Korean missile test wildly off course – could make the heavily armed peninsula explode.
Despite their spotted history, talks seem the only option. “No country has ever been coerced into giving up nuclear weapons, but many have been convinced to,” says Cirincione. None of them, however, were rogue states that already had nukes.
Missile to the moon
North Korea’s declaration in August that it intends to was . Experts say , but a lander is beyond their current technology.
Still, the nation looks determined, attempting satellite launches despite accusations that they are a front for missile development.
Are they? Every nation with a space programme once used launchers that doubled as missiles, and China still does, says John Schilling of Aerospace Corporation in California. He thinks North Korea’s space programme taught it about the multi-stage rockets it needs for long-range nuclear weapons.
But now, he says, space and missile development have parted ways. North Korea’s Unha-3 launcher has upper stages with small engines perfect for putting a satellite in orbit, but too weak for an intercontinental ballistic missile (ICBM).
Covert ops
Yet the North’s space ambitions can also further its military ones. To make a nuclear ICBM, the country needs a heat shield to protect the warhead on re-entry. They could test one covertly, suggests Schilling, by flying it on a “satellite” which falls to Earth.
We could soon see. North Korea just tested a larger booster engine that may launch later this year.
This article appeared in print under the headline “Ready for launch?”
