The nations of the world confront serious and immediate threats from the global presence of some 27,000 nuclear weapons. They also face the possibility that some nation or group still has or soon could have biological or chemical weapons. A wide variety of delivery mechanisms for these weapons exists, including ballistic missiles, cruise missiles, aircraft, artillery, ships, trucks, and envelopes. There is also now the added danger that terrorist organizations could kill thousands with these weapons or destroy or sabotage critical urban and industrial infrastructures.
While a terrorist attack on these infrastructures using conventional weapons is the most likely threat, the explosion of a nuclear weapon would be the most devastating. The formula of “risk times consequences” forces us to focus serious attention on this catastrophic possibility.
Nuclear threats lie along four axes, though development along one axis often influences developments along the others. The four categories of threat are nuclear terrorism, new nuclear weapon states and regional conflict, existing nuclear arsenals, and regime collapse. The greatest concerns are outlined here.
Nuclear Terrorism: The Most Serious
While states can be deterred from using nuclear weapons by fear of retaliation, terrorists, who have neither land, people, nor national futures to protect, may not be deterrable. Terrorist acquisition of nuclear weapons therefore poses the greatest single nuclear threat. The gravest danger arises from terrorists’ access to state stockpiles of nuclear weapons and fissile materials, because acquiring a supply of nuclear fuel (as opposed to making the weapon itself) remains the most difficult challenge for a terrorist group. So-called outlaw states are not the most likely source. Their stockpiles, if any, are small and exceedingly precious, and hence well guarded. (Nor are these states likely to give away what they see as the crown jewels in their security crowns.) Rather, the most likely sources of nuclear weapons and materials for terrorists are storage areas in the former states of the Soviet Union and in Pakistan, and fissile material kept at dozens of civilian sites around the world.
There is also a substantial risk of terrorist theft from the nuclear stockpiles in more than forty countries around the world. Many of these caches of materials consist of highly enriched uranium that could be directly used in nuclear weapons, or further enriched to weapons grade. There are also significant stockpiles of plutonium that can be used in a weapon, though with more difficulty.
New Nuclear Nations and Regional Conflicts
The danger posed by the acquisition of nuclear weapons by Iran or North Korea is not that either country would likely use these weapons to attack the United States, the nations of Europe, or other countries. States are and will continue to be deterred from such attacks by the certainty of swift and massive retaliation. The greater danger is the reactions of other states in the region. A nuclear reaction chain could ripple through a region and across the globe, triggering weapon decisions in several, perhaps many, other states. With these rapid developments and the collapse of existing norms could come increased regional tensions, possibly leading to regional wars and to nuclear catastrophe.
New nuclear weapon states might also constrain the United States and others, weakening their ability to intervene to avoid conflict in dangerous regions, as well as, of course, emboldening Tehran, Pyongyang, or other new possessors.
Existing regional nuclear tensions already pose serious risks. The decades-long conflict between India and Pakistan has made South Asia for many years the region most likely to witness the first use of nuclear weapons since World War II. There is an active missile race underway between the two nations, even as India and China continue their rivalry. In Northeast Asia, North Korea’s nuclear capabilities remain shrouded in uncertainty but presumably continue to advance. Miscalculation or misunderstanding could bring nuclear war to the Korean peninsula.
In the Middle East, Iran’s quest for nuclear weapons, together with Israel’s nuclear arsenal and the chemical weapons of other Middle Eastern states, adds grave volatility to an already conflict-prone region. If Iran were to acquire nuclear weapons, Egypt, Saudi Arabia, or others might initiate or revive nuclear weapon programs. It is possible that the Middle East could go from a region with one nuclear weapon state, to one with two, three, or five such states within a decade–with existing political and territorial disputes still unresolved. This is a recipe for nuclear war.
The Risk from Existing Arsenals
There are grave dangers inherent in the maintenance of thousands of nuclear weapons by the United States and Russia and the hundreds of weapons held by China, France, the United Kingdom, Israel, India, and Pakistan. While each state regards its nuclear weapons as safe, secure, and essential to its security, each views others’ arsenals with suspicion.
Though the Cold War has been over for more than a dozen years, Washington and Moscow maintain thousands of warheads on hair-trigger alert, ready to launch within fifteen minutes. This greatly increases the risk of an unauthorized launch. Because there is no time buffer built into each state’s decision-making process, this extreme level of readiness also enhances the possibility that either side’s president could prematurely order a nuclear strike based on flawed intelligence.
Recent advocacy by some in the United States of new battlefield uses for nuclear weapons could lead to new nuclear tests. The five nuclear weapon states recognized by the Non-Proliferation Treaty have not tested since the signing of the Comprehensive Test Ban Treaty in 1996, and no state has tested since India and Pakistan did in May 1998. New U.S. tests would trigger tests by other nations, seriously jeopardizing the CTBT, which is widely regarded as a pillar of the nonproliferation regime.
The Risk of Regime Collapse
If U.S. and Russian nuclear arsenals remain at Cold War levels, many nations will conclude that the weapon states’ promise to reduce and eventually eliminate these arsenals has been broken. Non-nuclear states may therefore feel released from their pledge not to acquire nuclear arms.
The Non-Proliferation Treaty is already severely threatened by the development in several states of facilities for the enrichment of uranium and the reprocessing of plutonium. Although each state asserts that these are for civilian use only, supplies of these materials potentially puts each of these countries “a screwdriver’s turn” away from weapons capability. This greatly erodes the confidence that states can have in a neighbor’s non-nuclear pledge.
Additionally, there appears to be growing acceptance of the nuclear status of Pakistan and India, with each country accruing prestige and increased attention from leading nuclear weapon states, including the United States. Some now argue that a nuclear Iran or North Korea could also be absorbed into the international system without serious consequence.
If the number of states with nuclear weapons increases, the original nuclear weapon states fail to comply with their disarmament obligations, and states such as India gain status for having nuclear weapons, it is possible that Japan, Brazil, and other major non-nuclear nations will reconsider their nuclear choices. Most nations would continue to eschew nuclear weapons, if only for technological and economic reasons, but others would decide that nuclear weapons are necessary for improving their security or status. There is a real possibility, under these conditions, of a system-wide collapse.
The Nuclear Nations
Today, only eight nations are known to have nuclear weapons. Five nuclear-weapon states are recognized by the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and enjoy special rights and privileges under international law. Listed in order of the size of their nuclear arsenals, they are: Russia, the United States, China, France, and the United Kingdom. This group acquired their arsenals during the twenty years after World War II and remained remarkably stable from 1964, when China tested its first nuclear weapon, until 1998, when India and Pakistan both detonated nuclear devices and declared their intention to deploy weapons. India and Pakistan have not yet openly deployed any weapons, but both are capable of configuring aircraft and missiles with tens of weapons over the next few years if they so desire. Israel is widely believed to have approximately 100 nuclear weapons but neither acknowledges nor denies their existence. India, Pakistan, and Israel are not parties to the NPT.
Apart from these eight countries, two others are known to be actively pursuing nuclear weapon programs. North Korea may have accumulated enough material to construct as many as ten weapons. The 1994 agreement that had frozen the nation’s plutonium program broke down in 2002 and North Korea announced its withdrawal from the NPT. Iran is slowly but steadily pursuing an open civilian nuclear power program and may be covertly developing expertise for nuclear weapons.
Since the signing of the Non-Proliferation Treaty in 1968, many more countries have given up nuclear weapon programs than have begun them. There are fewer nuclear weapons in the world and fewer nations with nuclear weapon programs than there were twenty years ago.
In the past twenty years, several major countries have abandoned nuclear programs, including Argentina and Brazil, and four others have relinquished their nuclear weapons to join the NPT as non-nuclear-weapon states. Ukraine, Belarus, and Kazakhstan gave up the thousands of nuclear weapons deployed on their territories when the Soviet Union dissolved, thanks in great measure to the dedicated diplomacy of the Bush and Clinton administrations. Similarly, South Africa, on the eve of its transition to majority rule, destroyed the six nuclear weapons the apartheid regime had secretly constructed. President Nelson Mandela agreed with the decision, concluding that South Africa’s security was better served in a nuclear-free Africa than in one with several nuclear nations, which is exactly the logic that inspired the original members of the NPT decades earlier. Iraq gave up its nuclear program after the 1991 Gulf war and subsequent UN disarmament efforts, though the United States led a coalition of nations to invade Iraq on the mistaken belief that the country still had major programs for nuclear, biological and chemical weapons. Libya gave up its nuclear and chemical weapons programs and long-range missile program in December 2003 after negotiations with the United States and the United Kingdom.
Radiological weapons, although not as destructive as nuclear explosive weapons, also pose a serious danger, particularly as a terrorist threat. These are weapons that use conventional explosives, such as dynamite, to disperse radioactive materials, including the highly radioactive waste material from nuclear power reactors or other nonweapon sources. They may be attractive weapons for terrorists owing to the relative ease of their acquisition and use and mass disruption potential.
Effective Policies Prevented Worse Dangers
President John F. Kennedy worried that while only the United States, the Soviet Union, the United Kingdom, and France in the early 1960s possessed nuclear weapons, by the end of the decade 15 or 20 nations would have them. The concern was not that developing countries would acquire the bomb, but rather that the advanced industrial nations would do so, particularly Japan and Germany. Several European nations were already actively pursuing nuclear weapon programs. Neutral Sweden, for example, was then developing plans to build 100 nuclear weapons to equip its air force, army, and navy.
Kennedy moved aggressively to counter those trends. United States diplomacy and international efforts to create legal and diplomatic barriers to the acquisition of nuclear weapons, codified in the Treaty on the Non-Proliferation of Nuclear Weapons in 1968, dramatically stopped the rush toward nuclear weapon status. Twenty years after Kennedy’s warning, only China (with Soviet help) had openly joined the ranks of the new nuclear nations while India had exploded a so-called peaceful nuclear device and Israel was building a secret nuclear arsenal. All the other nations that had studied nuclear programs in the 1950s and 1960s had abandoned their pursuits. The treaty did little at that time, however, to constrain the nuclear arms race between the two superpowers in the 1960s and 1970s that was sometimes known as vertical proliferation.
Non-proliferation efforts have steadily advanced over the past two decades, but never easily and never without serious setbacks. Although nuclear, biological, and chemical arsenals in the United States and the Soviet Union once grew to enormous levels and the technology of these weapons has become increasingly accessible, the world has not been devastated by a thermonuclear war. Moreover, the number of new prospective nuclear nations has shrunk dramatically over the past 20 years, not increased, and the international norm has been firmly established that countries should not, under any circumstances, possess or use either biological or chemical weapons. Global expectations are that the existing stockpiles of nuclear weapons will be greatly reduced, even if their eventual elimination seems but a distant hope.
Only four nations since 1964 have overcome the substantial diplomatic and technical barriers to manufacturing nuclear weapons. The proliferation of biological and chemical weapons is broader, but it is still mainly confined to two regions of the world: the Middle East and Northeast Asia. Most of the world’s biological weapons have been destroyed, and the bulk of the global chemical weapon arsenals will likely be eliminated over the next ten years.
With all the serious challenges that exist, the non-proliferation regime has still had a remarkable record of success. But can it hold? Or are international conditions so different today that the regime can no longer work?
Twenty-first Century Proliferation
The Bush administration implemented a radically new non-proliferation approach. Previous presidents had treated the weapons themselves as the problem and sought their elimination through treaties. President Bush framed the issue differently in his 2003 State of the Union address: “The gravest danger facing America and the world is outlaw regimes that seek and possess nuclear, chemical, and biological weapons.” (italics added) The administration changed the focus from “what” to “who,” seeking the elimination of regimes rather than weapons.
The first direct application of this theory was the war with Iraq. Since 2000, however, proliferation problems have grown worse, not better. Libya is an unqualified success, as that nation abandoned decades of work on nuclear and chemical weapons and missile programs. But Iran has accelerated its program — whether peaceful or not –in the past few years. So has North Korea. Globally, the threat from nuclear terrorism has grown as U.S. intelligence officials conclude that the Iraq war made the terrorism problem worse, and supplies of weapons and weapon materials remain dangerously insecure. While U.S. attention focused on the three “axis of evil” states, the nuclear black market of Pakistan’s A.Q. Khan spread nuclear weapon technology and know-how around the world. It is not clear if this network has shut down or merely gone further underground. Meanwhile, the United States and Russia have ended the process of negotiating reductions in their nuclear arsenals and the reductions themselves are proceeding at a slower pace than previous administrations planned. Finally, there is growing concern that the entire non-proliferation regime is in danger of a catastrophic collapse.
The strategy, or some modified variation, could still prove its worth. But a combination of approaches may offer the best chance of success. The European Union has crafted its own strategy that includes tying all EU trade agreements to observance of non-proliferation treaties and norms. This “soft power” approach could meld with the “hard power” of the United States to replicate the U.S-UK success with Libya. The Libya model could emerge from and prevail over the Iraq model: change a regime’s behavior rather than change the regime. The critical importance of the NPT and other treaties is that they provide the necessary international legal mechanism and establish the global norms that give nations a clear path to a non-nuclear future. Military solutions cannot work alone. No nation has ever been coerced into giving up a nuclear program–but many have been convinced to do so.
These historic lessons must be remembered anew, lest in our haste to construct new solutions we tear down the very structures we need only repair.
Joseph Cirincione is the Senior Vice-President for National Security and International Affairs at the Center for American Progress.
This article has been reprinted with permission from Forum on Physics & Society of The American Physical Society, Vol. 35, No. 3, July 2006.
 This is the danger President Kennedy warned of in 1963. “I ask you to stop and think for a moment what it would mean to have nuclear weapons in so many hands, in the hands of countries large and small, stable and unstable, responsible and irresponsible, scattered throughout the world,” he said. “There would be no rest for anyone then, no stability, no real security, and no chance of effective disarmament. There would only be the increased chance of accidental war, and an increased necessity for the great powers to involve themselves in what otherwise would be local conflicts.” John F. Kennedy, “Radio and Television Address to the American People on the Nuclear Test Ban Treaty,” July 26, 1963, available at http://www.jfklibrary.org/jfk_test_ban_speech.html (accessed December 10, 2004).
 Several countries in the Middle East are capable of pursuing nuclear weapon programs or otherwise acquiring nuclear weapons, including Saudi Arabia, Egypt , and Turkey . Saudi Arabia might seek to purchase nuclear weapons from Pakistan , or invite Pakistan to station nuclear weapons on its territory. Other countries have at least the basic facilities and capabilities to mount a nuclear weapon program, albeit not without significant political and economic consequences. Egypt and Turkey could probably acquire enough nuclear material to produce a nuclear weapon within a decade of launching such an effort.
 Former U.S. Senator Sam Nunn argues, “The more time the United States and Russia build into our process for ordering a nuclear strike the more time is available to gather data, to exchange information, to gain perspective, to discover an error, to avoid an accidental or unauthorized launch.” Speech to the Carnegie International Non-Proliferation Conference, June 21, 2004, available at www.ProliferationNews.org.
 Six nations abandoned indigenous nuclear weapon programs under way or under consideration in the 1960s: Egypt, Italy, Japan, Norway, Sweden, and West Germany. Since the late 1970s, Argentina, Australia, Belarus, Brazil, Canada, Iraq, Kazakhstan, Libya, Romania, South Africa, South Korea, Spain, Switzerland, Taiwan, Ukraine, and Yugoslavia have abandoned nuclear weapon programs or nuclear weapons (or both) on their territory. North Korea and Iran are the only two states that began acquiring nuclear weapon capabilities in this later period and have not ceased the effort.
 In 1970, the year the NPT entered into force, there were about 38,000 nuclear weapons in global arsenals, mostly in the stockpiles of the United States and the Soviet Union; by 1986, the number of weapons had increased to a peak of 65,000 worldwide; in 2004, there were approximately 27,000.
 See testimony of Central Intelligence Director Porter Goss and Defense Intelligence Agency Director Admiral Lowell Jacoby before the Senate Intelligence Committee, February 16, 2005.