In the 75 years since dropping atomic bombs on the Japanese cities of Hiroshima and Nagasaki to end World War II, the United States has sought to limit the spread of these weapons to other countries. Successive presidents have made nuclear nonproliferation a consistent and important American purpose, and for good reason. Not only would the spread of these armaments reduce the relative power of the United States, their diffusion would increase the chances of the ultimate horror—a nuclear war. The greater the number of countries that have them, the greater will be the likelihood that one, or many, nuclear shots will be fired in anger, causing untold death and destruction.
At the height of the Cold War, nonproliferation was one of the few goals on which the United States and its rival, the Soviet Union, could agree. Accordingly, they negotiated the Nuclear Nonproliferation Treaty (NPT) in 1968 and eventually persuaded most other sovereign states to sign it, by which the others promised not to acquire such weapons for themselves. The distinction of being history’s most effective anti-proliferation measure, however, belongs not to the NPT but to the American system of alliances. Countries that could have built their own bombs have decided against doing so because they have felt adequately protected by American security guarantees. America’s post-World War II global leadership succeeded in engendering enough confidence in the reliability of the United States to prevent widespread nuclear proliferation.
That confidence will face major challenges in the near future in three important parts of the world. Aggressive powers in each – Russia in Europe, Iran in the Middle East, and China in East Asia – are all too likely to conduct policies that will present the United States, in each region, with an agonizing choice: undertaking difficult and dangerous military operations or, by failing to do so, causing friendly countries to decide that their safety and well-being require having their own nuclear arsenals. Such choices could well dominate the foreign-policy agenda of whoever wins the November presidential election.
With his popularity declining and opposition to his autocratic rule rising, the Russian dictator Vladimir Putin will be tempted during the next four years to employ a tactic that has raised his standing among Russians in the past: attacking a neighboring country. In 2014, his forcible seizure of the Crimean Peninsula from Ukraine and occupation of the eastern part of that country sent his popularity soaring. The obvious targets for a repeat performance are one or more of the three Baltic countries – Estonia, Latvia, and Lithuania. Each is tiny compared to Russia, each shares a border with its giant neighbor, each contains an ethnic Russian minority, and each belongs to the American-led Western military alliance, the North Atlantic Treaty Organization (NATO). None could be easily defended against a determined Russian assault.
Launching such an assault would represent a huge gamble for Putin, but if he did make it the United States would confront the task of fighting at a distinct geographic disadvantage against a nuclear-armed adversary. If Russia succeeded in conquering any of the three, or even occupying a piece of one of them, this would deal a deadly blow to NATO. Western Europeans could no longer be certain that the United States would defend them. Confronting a Russia that would look far more menacing to them in the wake of an attack on any or all of the Baltic countries, at least some Europeans would likely calculate that they needed nuclear weapons of their own to offset those that Moscow controls. Great Britain and France have long been members of the club of nuclear-weapon states, but it is far from clear that other Western Europeans, particular the Germans, would regard the British and French arsenals as sufficient protection for themselves. In the early decades of the Cold War, the United States made it a high priority to persuade its West German ally not to acquire nuclear weapons because American officials believed that such a development would seriously destabilize Europe. If NATO failed to protect the Balts, what a previous generation of American policymakers feared would in all probability come to pass.
In the Middle East, Iran is actively seeking to dominate its neighbors and has already made considerable progress toward achieving this goal. The 2015 nuclear deal with the United States – the Joint Comprehensive Plan of Action (JCPOA) – led, if anything, to an acceleration of this campaign of domination. Nor could that agreement have permanently stopped the Islamic Republic’s drive to acquire nuclear weapons, for its key provisions had expiration dates after which Iran could pursue the bomb without violating the JCPOA. The Trump Administration withdrew from the agreement, and former Vice President Biden has promised to re-enter it. But neither course can ultimately spare the world from the danger of Iranian nuclear weapons. Should it acquire them, other Middle Eastern countries – probably Saudi Arabia, Turkey, and Egypt, but perhaps also some of the smaller oil sheikhdoms of the Persian Gulf – most of them already threatened by Iranian ambitions, would almost certainly proceed as quickly as possible to equip themselves with nuclear armaments.
This would create the most dangerous of all possible nuclear conditions. During the Cold War, the United States and the Soviet Union managed to avoid a nuclear exchange in no small part because there were only two of them, each had a large nuclear arsenal that could survive a surprise attack by the other, and they were geographically distant from each other. A nuclear Middle East would have none of these buffers against nuclear combat. It would have several nuclear-weapon states, located close to one another, armed with small nuclear forces. In a crisis, each country involved would feel a powerful temptation to launch a preemptive attack.
With or without a revived JCPOA, Iran will continue its efforts to build nuclear weapons, and it will fall to the United States to prevent it from doing so, which, in all likelihood, will require the use of force. This would not require putting American troops on the ground; but it would involve a major campaign of aerial bombardment against Iran’s nuclear facilities. The next president may not be able to avoid the choice between launching such a campaign and suffering the consequences of the nuclearization of a region on which the world still heavily depends for the oil needed for its economies to function.
In East Asia, the Chinese Communist leader Xi Jinping is presiding over that country’s most aggressive foreign policy since the days of Mao Zedong, but with far more military power. Like Putin in Russia, Xi relies on assertive nationalism to bolster his standing in the face of a declining rate of economic growth. For this purpose, he, like Putin, has an obvious target: in the Chinese case the island of Taiwan – democratic, prosperous, and effectively independent since 1949 but claimed by the Communist authorities in Beijing as part of China and thus theirs to rule.
Taiwan has enjoyed the protection of the United States – first by the terms of a formal treaty and then through less formal understandings – and also from the 100-mile-wide Taiwan Strait that separates it from the mainland, across which the Communist government would have to launch an amphibious assault to take control of the island. Beijing has invested heavily in amassing the military capacity to mount a cross-Straits military operation. In the not-too distant future, the combination of the Beijing regime’s military strength and domestic political pressure on it could trigger a cross-Straits attack.
In that case, if the United States failed to defend Taiwan or tried but failed to defend it, all the countries of East Asia that rely on American protection would have to recalibrate their security policies. As in the other two regions, a dramatic success for the aggressive power in East Asia would likely set off a “proliferation cascade,” with several other countries – Japan, despite its national aversion to nuclear weapons stemming from its experience in 1945, and also South Korea but perhaps others as well – equipping themselves with nuclear weapons to deter China and defend their own freedom of action.
That grim prospect raises questions that have not been seriously posed for the last 75 years. If a mainland Chinese conquest of Taiwan would transform East Asia in an entirely undesirable way, if the United States cannot be relied on to prevent this from taking place, and if the surest way for a country to guarantee its own independence is to have its own nuclear weapons, would it be advantageous for Taiwan to acquire a nuclear arsenal in anticipation of a Chinese attack, in order to deter it? This might not prevent other East Asian countries from acquiring nuclear weapons of their own, but it might ensure that the nuclearized region included a free Taiwan. If such a development is indeed advisable, should the United States assist Taiwan in becoming a nuclear power? Every administration since 1945 would have dismissed that question as foolish at best and dangerous at worst. The next president may not have the luxury of waving it away.
Michael Mandelbaum is the Christian A. Herter Professor Emeritus of American Foreign Policy at The Johns Hopkins School of Advanced International Studies in Washington, D.C. and the author of three books about nuclear weapons: The Nuclear Question, The Nuclear Revolution, and The Nuclear Future.
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