In Nuclear war

By Debora MacKenzie, New Scientist, Sept 20, 2017  (in print issue #3144, Sept 23, 2017)

The sabre-rattling between Pyongyang and Washington is masking a dangerous destabilisation in deterrence – making nuclear war by accident a real possibility

AS YOU read this, about a dozen submarines are lurking in the world’s oceans, equipped to launch nuclear missiles. Four are American; the rest might be British, French, Russian, Chinese, Indian or perhaps Israeli. Some of them are packing massive heat, equivalent to thousands of times the bomb that obliterated Hiroshima. All are being very, very quiet.

HMS Vengeance is new newest of four British submarines armed with Trident nuclear-armed missiles

Why? In a word, deterrence. In the event of a nuclear strike or massive conventional attack on the sub’s owner or its allies, that nation can unleash horrendous retaliation – so no one dares attack in the first place.

Deterrence is credited with preventing nuclear conflict since the beginning of the cold war, but it is under increasing stress. Most obviously, North Korea has entered the game. It says it is developing nuclear weapons precisely to deter a US nuclear strike, but with the rhetoric getting out of hand, nuclear conflict could become more likely rather than less.

But beyond that headline news lies a less well-known, but potentially more disturbing, story. A series of seemingly minor technological upgrades have been destabilising the foundations of deterrence, sparking a new nuclear arms race with unforeseeable consequences. “The danger of an accident leading to nuclear war is as high now as it was during periods of peak crisis during the cold war,” says Hans Kristensen, director of the Nuclear Information Project at the Federation of American Scientists.

The rules of deterrence as formulated in the cold war depend on guaranteed retaliation to any nuclear strike. If an enemy can knock out your ability to retaliate by launching a surprise first strike on your nuclear missiles – called a counterforce attack – deterrence fails (see “Will they, won’t they?”).

Hence the silence of the nuclear subs, and the existence of nuclear missiles on mobile launchers hidden in forests or tunnels in Russia, China, India, Pakistan, Israel and soon, North Korea: if they cannot be found, they cannot be taken out in a first strike. Hence the US and Russian principle of maintaining a “triad” of submarine, land-based and airborne weapons: if one is knocked out, the others can strike back.

The world’s nuclear arsenals (image on New Scientist)

Hence also why the US and Russia keep 400 and 136 intercontinental ballistic missiles (ICBMs) in silos and on hair-trigger alert, so they can be launched at the first sign of incoming missiles that might destroy them. There used to be far more, before the Strategic Arms Reduction Treaty or START process began progressively cutting the arsenals of the two main nuclear powers in the 1990s. But there are still so many that no counterforce attack can knock them all out.

That was the theory anyway – but it’s one that seems increasingly at odds with reality. Besides its land-based ICBMs, the US packs 890 warheads on submarine-launched missiles. Of these, 506 are code-named W76, and each has the explosive power of 100 kilotonnes of TNT. The rest, called W88s, pack 455 kilotonnes. (The Little Boy bomb dropped on Hiroshima delivered 15 kilotonnes.)

Trident missiles can release up to eight of these warheads above the atmosphere, which then fly independently to preset targets. Barring mechanical failure, the warheads should detonate within 100 metres of their targets. For the big W88s, that is close enough to destroy a “hard” site like a concrete ICBM silo. The smaller W76s have to land closer. As a result, W76s have previously been aimed at soft targets, like military bases, where accuracy is less crucial.

But in 1998, the US Navy started developing a “super-fuse” for the W76s that measures and corrects for their altitude at release, making them three times more likely to explode close enough to the target to destroy it. The US started deploying the super-fuse in 2009. In March this year, Kristensen and his colleagues published calculations showing that this apparently small change to US submarine-launched nuclear missiles means they can now take out all Russia’s ICBM silos using just over half of the W76s, even aiming two warheads at each in case some are faulty. “That frees up the rest, and the heavier W88s, to take on harder targets such as buried command and control bunkers,” Kristensen says.

All W76 warheads on the US submarine fleet are now fitted with these fuses, and they are thought to have been delivered recently to the UK’s Tridents, says Paul Ingram of the British American Security Information Council, a think tank in London. A similar fuse will start being fitted to US land-based ICBMs in the 2020s.

The super-fuse upgrade was part of the US nuclear modernisation programme, which is supposed to ensure the reliability of the US nuclear arsenal, not boost its capability. But after the cold war, military demands were diversifying and growing, even as the START process cut the number of warheads. So planners wanted more efficient warheads – and technology supplied that. “The super-fuse seemed such a minor change that policy-makers missed the serious implications for strategic stability and perceptions of US intentions,” says Kristensen. “It’s an astonishing, game-changing increase in US nuclear capability.”

Escalating fears

Just because the US may now be more able to take out another country’s nuclear deterrent doesn’t mean it plans to, of course. But in the game of deterrence, what matters is perceptions. James Acton of the Carnegie Endowment for International Peace, a think tank in Washington DC, thinks the US would be very unlikely to try a first strike. It would not find and destroy all of Russia or China’s mobile land-based or submarine missiles, and those that survived would be used to retaliate. “But many experts [in Russia and China] are deeply, genuinely worried about the survivability of their nuclear deterrent, and even if such fears are exaggerated they can drive escalation.”

The growth in US missile defence systems is also stoking these fears. These undermine deterrence by, in theory, allowing a country to launch a first attack safe in the knowledge that it can intercept any retaliatory strikes. In May this year, apparently in response to accelerated nuclear missile development by North Korea, the US conducted the first successful test – against a simulated ICBM – of the Ground-based Midcourse Defense system it has been developing since 1999.

In response, China made angry accusations that this would “start a new arms race”. Last year the Russian president, Vladimir Putin, made the same charge, naming US “high precision weapons” – an apparent reference to the super-fuse – plus missile defence as the reason.

As worries about vulnerability have grown, all sides have beefing up their deterrents. In 2015, China caught up with other nuclear powers by deploying missiles with multiple independent warheads. In November last year, Russia started tests of an underwater drone designed to explode a radioactive “dirty bomb” in an enemy harbour to contaminate a city. The plans were deliberately leaked in 2015, experts believe, to deter US missile defence plans by demonstrating alternative forms of retaliation for a first strike.

But efforts to reinforce deterrence with a new arms race could make the use of nuclear weapons more likely, rather than less. All sides are now developing manoeuvrable hypersonic missiles, to evade missile defences and early warning radar. The US says its missiles won’t be nuclear, but an adversary about to be hit by one won’t be able to tell. China says it is considering abandoning its policy of never using nuclear weapons first, precisely because of hypersonic missile development in the US.

Faced with a crisis such as an incoming hypersonic missile, a country may well launch its nuclear weapons fast if it thinks it may otherwise lose them in a counterforce strike, as well as to deter further attack, says Acton. Just one missile to convince the other side to back down might provoke retaliation instead. “It’s a low-probability event, but the consequences could be catastrophic,” he says. Increasing fears that the US is aiming to be able to win a nuclear first strike could make such reactions more likely – including now from the demonstrably paranoid regime in North Korea (see “The Korean question”).

You don’t even need a crisis – you just have to be wrong about signals that seem to suggest imminent attack. Now that the cold war satellites that Russia once used to sense heat plumes over US missile sites and warn of ICBM launches are defunct, its radar gives only 15 minutes’ warning of incoming rockets – half the time available to the US – and Russia cannot check where they came from.

That increases the possibility of a mistake. In 1995, Russian submarines came within 5 minutes of launching nuclear missiles after Moscow feared a Norwegian research satellite was an incoming Trident missile. Boris Yeltsin, then president, overruled his generals who advised launch, because the generally good relations between the US and Russia at the time seemed to preclude an attack. With the current atmosphere of mutual suspicion, we may not be so lucky now. That’s before you consider the increasingly real possibility of computers going haywire and launching nuclear attacks by themselves (see “Cybergeddon?”).

Uncharted territory

Submarine-launched nuclear missiles have long been considered the ultimate deterrent – and are the only one the UK has – because of their apparent invulnerability to pre-emptive strike. But even that now seems less certain. Persistent rumours of Soviet-era technology that allows nuclear subs to be tracked using their turbulent wakes may have something in them.

Going the other way, Ingram points to aircraft being developed for the US Navy by UK defence company BAE Systems. These can track submarines from the air using a drone to sense magnetic anomalies, then target them with air-launched missiles. If this system struck, say, a Russian submarine, the situation might not be clear in Moscow for some time, as these subs stay silent. Knowing that can happen increases Russian uncertainty, and further destabilises any potentially nuclear confrontation.

This has long been the paradox of deterrence: it is only ever a temporary stand-off, lasting just until the enemy finds a way to neutralise your deterrent. Ultimately, the technological capacity to see, hear and otherwise detect and destroy other countries’ weapons could become so good that first strikes will become winnable, and deterrence will no longer work. That seems to be the dangerous, uncharted territory we are now entering.

What else will keep the nuclear peace? Optimists are promoting a UN treaty to ban all nuclear weapons, released in May. Otherwise, say weapons experts, we can talk, reassure countries that their deterrents still work, and build confidence by creating channels of communication and sharing new weapons developments. But that, says Acton, is unlikely any time soon. “Neither the Russians nor the Chinese want to talk, though the Obama administration tried repeatedly. Now that’s over too.” And don’t even talk about North Korea.

* * *

Will they, won’t they?

The advent of nuclear bombs and their terrifying destructive capabilities turned the logic of conflict on its head. As the US military strategist Bernard Brodie wrote in 1946: “Thus far the chief purpose of our military establishment has been to win wars. From now on its chief purpose must be to avert them.”

But how? The answer was developed by game theorists in the 1950s: bat the ball into your opponents’ court. If you can convince them that any nuclear attack on you or your allies is suicidal, they won’t try it. But you must make sure your nuclear deterrent cannot be taken out before you can retaliate, and ensure the response is automatic – if you are hit, you will hit back.

That requires a lot of warheads, and led to the cold war arms race. At its height, any nuclear exchange would have meant the mutually assured destruction of the US and Soviet Union, fittingly known as MAD. Lesser deterrents, such as the UK’s, merely threaten something an enemy values, like a city.

However the game is played, deterrence has kept the nuclear peace since 1945, despite some hairy moments. Yet changing technology now threatens to destabilise this improbable saviour (see main story).

The Korean question

For all its ability to make headlines, most recently detonating what appears to have been a hydrogen bomb, North Korea is a bit player in the global game of nuclear deterrence. But its reason for going nuclear at all is to deter a first strike by the US. Like the big powers, it too worries that its nascent deterrent might be vulnerable.

North Korea has not yet attached a nuclear warhead to a missile and launched it. But it already has land-based medium-range missiles, and is developing an intercontinental ballistic missile, both of which can be moved by road. Typically countries keep these in bases, then deploy them in crises to forests or mountains where they can’t be seen by remote-sensing satellites. North Korea’s terrain is ideal – but moving them by road is risky.

Keir Lieber of Georgetown University in Washington DC and Daryl Press of Dartmouth College in New Hampshire have used public data from US polar-orbiting radar satellites and software such as OpenStreetMap to calculate that 90 per cent of North Korean roads are visible to satellites. The regime could move its missiles when satellites are not overhead, but Lieber calculates that 54 per cent of its roads would still be visible via radar to aerial drones operating outside North Korean airspace. That could rise to 97 per cent with extra input from stealthy drones that can operate briefly inside the country, which the US is developing.

To keep its deterrent safe, North Korea is developing submarine-launched missiles. For now, the deterrent might seem vulnerable to a first strike. But it would have to be 100 per cent successful to preclude nuclear retaliation, and there are too many uncertainties to guarantee that, says James Acton of the Carnegie Endowment for International Peace in Washington DC. And even then there are many other ways North Korea might retaliate, with its chemical or long-rumoured biological weapons, or the hundreds of conventional short-range missiles it has trained on the South Korean capital, Seoul.

The fact that North Korea’s nascent nuclear force could be vulnerable to a pre-emptive strike may just ensure that it keeps multiplying its nuclear weapons and delivery systems, and maintains other deterrents. And, as with its recent cautions about a warning shot at the US Pacific base at Guam, it will continue to find ways to let us know it has them.


In June 2016, the British submarine Vengeance test-fired a Trident missile, the UK’s nuclear deterrent. Something went badly wrong, and the missile may have veered towards the US.

The missile was not carrying its nuclear warheads and was destroyed. The UK government has remained silent on what might have caused the incident, but “the failed Trident test is consistent with cyber interference,” says Paul Ingram of the British American Security Information Council, a think tank in London.

It highlights another threat to the delicate balance of nuclear deterrence (see main story): hacking. Just the possibility that the computer systems controlling deterrents could be compromised is destabilising. But in June this year Ingram and Stanislav Abaimov, a Russian-trained hacking expert, concluded that the UK Trident-based deterrent is vulnerable to the cyberwar operations of foreign governments, despite its computers being separated from the internet. This is partly because of the many subcontractors that develop them; Vengeance had just had a major refit.

The US uses similar technology, so is potentially similarly vulnerable. Meanwhile Andrew Futter at the University of Leicester, UK, raises another problem. The command and control system used to manage US nuclear weapons is currently undergoing an upgrade. Parts of the old system still relied on 8-inch floppy discs. Although outdated, this was at least relatively simple. Futter worries that the spiralling complexity of the replacement not only provides hackers more toeholds, but could lead to errors that might not be immediately obvious, for example generating false alarms that could unleash a retaliatory strike.

In June, four former high-ranking US, Russian and European defence officials called on presidents Trump and Putin to start talks about “interference in strategic warning systems and nuclear command and control” to prevent war by mistake. “That there are no clear ‘rules of the road’ in the strategic nuclear cyberworld”, they wrote, for instance providing for consultations between adversaries, “is alarming.”

* * *

This article appeared in print under the headline ‘Accidental Armageddon’. Debora MacKenzie is a New Scientist correspondent based in Geneva. New Scientist is published weekly in Britain; subscription information is here.

Note by New Cold
Missing from the above article is the history of the United States abrogating treaty obligations to limit the spread and restrict the technology of nuclear arsenals, for example its 2002 withdrawal from the Anti-Ballistic Missile Treaty. This history explains, in part, why Russia and China abstained from the historic resolution of the UN General Assembly on July 7, 2017 to ban nuclear weapons. The U.S., Britain, France and their allies (Canada, Australia, etc) abstained from that vote for their own reasons of nuclear brinkmanship.

Also missing is explanation of how countries such as Israel, Pakistan and India came to acquire the nuclear fuel and the technology to develop a nuclear arsenal. In contrast to North Korea, none of these states is threatened by the United States with war and nuclear weapons. (See ‘Nuclear Proliferation’, Wikipedia.)

Background, from Wikipedia:
Anti-Ballistic Missile Treaty  (1972)
START I Treaty  (1991)
START II Treaty  (1993)

Further related reading:
The July 7, 2017 UN General Assembly vote to abolish nuclear weapons, report on New Cold

Canadian woman who survived Hiroshima bombing, shares recent Nobel Peace Prize, urges change of heart from Trudeau on nuclear weapons abolition, by Laura Stone, Globe and Mail, Oct 26, 2017

Trudeau replies to Hiroshima survivor campaigning for nuclear weapons abolition, by Laura Stone, Globe and Mail, Oct 27, 2017

North Korea rouses S Korea, Japan to reconsider nuclear weapons, by David E Sanger, Choe Sang-Hun and Motoko Rich, New York Times, Oct 28, 2017

… For the first time in recent memory, there is a daily argument raging in both South Korea and Japan — sometimes in public, more often in private — about the nuclear option, driven by worry that the United States might hesitate to defend the countries if doing so might provoke a missile launched from the North at Los Angeles or Washington.

In South Korea, polls show 60 per cent of the population favors building nuclear weapons. And nearly 70 per cent want the United States to reintroduce tactical nuclear weapons for battlefield use, which were withdrawn a quarter-century ago. There is very little public support for nuclear arms in Japan, the only nation ever to suffer a nuclear attack, but many experts believe that could reverse quickly if North and South Korea both had arsenals.


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