COMMENT ILLUSTRATION BY PETE ELLIS/DRAWGOOD.COM PETE BY ILLUSTRATION A call for global nuclear disarmament Danger from nuclear weapons is mounting. It is time to take control of the nuclear fuel cycle and move towards a world without warheads, says Scott D. Sagan. eclassified documents have revealed Fifty years on, we live in a nuclear world increasingly vulnerable to theft and use by that the 1962 Cuban missile crisis that has not just two superpowers but nine terrorists. was far more dangerous than anyone nuclear-weapons states, with new ones loom- Looking at this prospect, some politi- Dknew at the time. An American U-2 spy plane ing on the horizon (see ‘World of weapons’). cians and analysts have optimistically accidentally flew into Soviet airspace and US The governments of these emergent nuclear argued that new nuclear powers will behave fighter jets armed with nuclear-tipped mis- states may not make the same mistakes that cautiously and that a stable form of global siles entered the Bering Strait to rescue it. US Russia and the United States made during the nuclear deterrence is likely. For example, Minuteman missile controllers jury-rigged cold war, but they will make others. in 2007 Jacques Chirac, then president of their systems so that they could launch the We have entered a grave new world France, told the press that it “would not be nuclear missiles on their own if necessary. where governments believe that shielding very dangerous” if Iran obtained nuclear Pentagon planners began preparing for the themselves with their nuclear weapons will weapons. If Iranian leaders ever used possible invasion of Cuba, totally unaware allow them to engage more safely in aggres- the bomb, he argued, Tehran would be that Soviet tactical nuclear weapons were sive action, and increase nuclear prolifera- destroyed immediately in retaliation3. Oth- already deployed on the island and that local tion by selling their ers are more pessimistic and insist that the commanders had the authority to use them1. technology to other NATURE.COM only way to counter nuclear proliferators US President John F. Kennedy and Soviet Pre- governments. And More on scientific such as Iran is through preventive military mier Nikita Khrushchev avoided nuclear war it is a world where steps to nuclear operations. But such attacks are unlikely to in October 1962, but we now know how close nuclear materials and disarmament: be completely effective, could trigger wider they came to disaster2 (see page 27). weapons are becoming go.nature.com/sxcyne wars and, over the long term, could actually 30 | NATURE | VOL 487 | 5 JULY 2012 © 2012 Macmillan Publishers Limited. All rights reserved COMMENT encourage the spread of nuclear weapons. they take the territories that were occupied its nuclear programme, some politicians Neither passivity nor preventive war are after 1967?”6 In the late 1970s, Saddam told and analysts advocate air strikes — or even likely to lead to a safer nuclear future. Given Iraqi leaders that owning nuclear weapons a preventive war — against the country. An the gravity of the risks we face, careful and would permit Iraq to launch a conventional attack, however, would have serious global steady movement towards global nuclear war against Israel without the fear that Tel economic costs, cause many Iranian civilian disarmament should be our goal. The com- Aviv would, in desperation, retaliate with its casualties and would be unlikely to solve the plex and global nature of emerging nuclear nuclear arsenal. The transcript of Saddam’s problem. Preventive attacks can invigorate dangers will require complex and global solu- secret speech is chilling: “We can guarantee rather than destroy a covert nuclear-weapons tions. Scientists, engineers and governments the long war that is destructive to our enemy, programme. We learned this in 1981, when must work together to improve verification and take at our leisure each metre of land Israeli jet fighters bombed Iraq’s only nuclear of nuclear disarmament and to strengthen and drown the enemy with rivers of blood.”7 reactor, and Saddam then started a better- international control of uranium enrichment The world is fortunate that Saddam was funded and more covert nuclear-weapons and plutonium reprocessing technologies. forced to destroy his nuclear programme programme based after the 1991 Gulf War. “The choice on secret uranium- EMERGING DANGERS North Korea poses a serious nuclear is between enrichment facilities8. The dangers of the emerging nuclear land- threat. Its government has behaved aggres- a world free Fortunately, we are scape can be seen clearly in Pakistan. Within sively since conducting its first nuclear test of nuclear not yet at the crisis months of testing its first nuclear weapon in in 2006, and a second in 2009. In 2010, it weapons or point when the only May 1998, the Pakistani military sent sol- was accused of sinking a South Korean Navy one with many options are to attack diers disguised as mujahedin guerillas into vessel, the Cheonan, which killed 46 seamen. more nuclear Iran or live with a Indian-held Kashmir, a move that sparked North Korean artillery shelled the South states.” nuclear-armed Iran. the 1999 Kargil War and led to a series of Korean island of Yeonpyeong in November The global policy nuclear threats between New Delhi and that year, killing two marines and two civil- objective should be to push the day of reck- Islamabad. Pakistani nuclear scientist Abdul ians. In addition, North Korea is such an eco- oning over the distant horizon. We must Qadeer Khan then established an infamous nomic basket case that it seems willing to sell create time for sanctions and cyber-sabotage network that sold centrifuge technology to almost anything: from counterfeit currency, to delay Iran’s progress, raise the costs of its Iran, North Korea and Libya. Pakistan also fake pharmaceuticals and illicit drugs to the unwillingness to constrain its enrichment highlights the risks of nuclear terrorism: the more lucrative business of smuggling mis- programme, and enable diplomatic initiatives army is fighting internal Pakistani Taliban sile and nuclear technology. North Korean to be effective. A potential negotiated settle- threats and has been penetrated by Islamist leaders may not sell actual nuclear bombs ment could include agreement for regular radical insiders4. to other countries — they have only enough international inspections but allow Iran to Islamabad is aware of these dangers and nuclear material for a handful of weapons keep the Natanz uranium-enrichment cen- has strengthened security measures, some for their own country’s use — but they have tre and a store of low-enriched uranium. This with US assistance, including steps to ensure shipped missiles without nuclear warheads would not be ideal because it would leave Iran the reliability of its personnel and to protect to Pakistan and Iran. They were also caught with a long-term nuclear break-out option. its nuclear arsenal from terrorists while the secretly selling uranium hexafluoride (used But it would be better than a preventive attack weapons are stored in bunkers at military to make nuclear reactor fuel, or a bomb) to or blind faith in nuclear deterrence. bases5. Yet a dangerous ‘vulnerability– Libya in 2004 and a plutonium production Nuclear weapons may have been a danger- invulnerability paradox’ remains. In a future reactor to Syria in 2007. ous necessity to ensure the cold war stayed crisis with India, the Pakistani military is cold. But scholars and policy-makers who likely to place its nuclear arsenal on alert, IRAN’S NUCLEAR SHIELD are nostalgic for the brutal simplicity of mating the warheads with mobile missile Why should we worry about a nuclear Iran? that era’s nuclear deterrence do not under- launchers and moving the missiles outside The gravest danger is not that leaders in Teh- stand how much the world has changed. its bases and into field positions. This opera- ran will order a suicidal nuclear first strike The choice we face today is not between a tion would make Pakistan less vulnerable on Israel or the United States. The real dan- nuclear-weapons-free world or a return to to attack by India, but make the weapons ger is that if Iran acquires nuclear weapons, bipolar cold war deterrence, but between a far more vulnerable to seizure by terrorists. leaders in Tehran will see them as a shield world free of nuclear weapons or one with Similar nuclear dangers can be seen in behind which they can engage in conven- many more nuclear states. Iraq, which tried and failed to develop the tional and terrorist aggression. bomb. We now know, from documents Iran is already a major arms supplier to ROAD TO DISARMAMENT captured after the fall of Baghdad in 2003, Hezbollah, the Lebanon-based Shi’a mili- The technical and political challenges that Saddam Hussein abandoned his secret tia, and supports its attacks against civilian that confront proponents of nuclear dis- nuclear-weapons-development programme and military targets inside Israel and other armament are complex and serious. We after UN inspectors discovered it in the Middle Eastern countries. Iran also covertly lack adequate disarmament-verification wake of the first Gulf War. But we can learn armed Iraqi Shi’a militia fighting US troops technology, such as techniques to permit important lessons about how new nuclear- in Iraq. Moreover, the Islamic Revolution- remote sensing of covert weapons-related weapons states might act by studying how ary Guard Corps — responsible for run- activities. Some allies rely on extended Saddam envisioned using nuclear weapons ning Iran’s operations in support of terrorist nuclear security guarantees — US com- as a shield for aggression towards other organizations — controls the nuclear pro- mitments to retaliate with nuclear weap- nations.