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Will anyone push the button? The credibility of nuclear threats

By Matthew Fuhrmann, visiting associate professor at the Center for International Security and Cooperation at Stanford University and associate professor at Texas A&M University, and Todd S. Sechser, associate professor at the University of Virginia

President Trump asserted recently that the United States must be “at the top of the pack” when it comes to nuclear weapons. What would greater nuclear firepower buy the United States?

Much less than the president seems to think.

In our newly published book Nuclear Weapons and Coercive Diplomacy, we analyzed the benefits that the United States and other nuclear powers derive from possessing nuclear arsenals. We reached a surprising conclusion: nuclear weapons (and nuclear superiority) have rarely, if ever, caused countries to win international crises.

History reveals the limitations rather than the virtues of nuclear weapons for coercive diplomacy. Soviet premier Nikita Khrushchev tried — and failed — to expel Western forces from Berlin between 1958 and 1961 by threatening to unleash a nuclear war. Pakistani leaders have been unable to seize disputed territory from India despite making nuclear threats, including during a limited war fought in 1999. More recently, Kim Jung Un’s brazen nuclear threats haven’t resulted in significant political gains for North Korea.

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Even cases that seemingly support Trump’s logic fail to provide smoking gun evidence. Consider the 1962 Cuban missile crisis. The United States compelled the Soviet Union to dismantle missile sites in Cuba after the two superpowers came to the brink of nuclear war. It may seem that Moscow caved because it had an inferior nuclear arsenal. But President Kennedy didn’t seem to think that nuclear superiority mattered: “What difference does it make,” he said during the crisis, “They’ve got enough [nuclear weapons] to blow us up now anyway.”

Nuclear weapons are poor tools of international influence, despite their destructive power, because it is difficult to make nuclear threats believable. Coercive nuclear threats — those that seek to overturn the existing status quo rather than defend it — give rise to particularly acute credibility problems:

  1. Carrying out a nuclear threat would be tremendously costly for the attacker. It might invite political blowback, establish a dangerous precedent, and foment nuclear proliferation. Nuclear powers may accept these costs in order to defend their homelands or protect other critical national interests. But this leads to a second factor that weakens the credibility of coercive nuclear threats.
  2. The stakes in coercive diplomacy are rarely vital for the coercer. States may attempt to gain control over disputed territory or force an opponent to change an undesirable policy. These issues are surely important — they would not precipitate crises otherwise — but they are not fundamental enough to offset the costs of shattering the 72-year tradition of nuclear non-use.

The high costs of attacking for relatively low stakes make it easy for potential adversaries to dismiss coercive nuclear threats — even when the target country operates from a position of nuclear weakness. To illustrate, the United States currently has a larger and more powerful arsenal than China. By Trump’s logic, this should enhance Washington’s influence over Beijing. It doesn’t. Most nuclear threats the United States could make against China lack credibility.

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Take the ongoing dispute over control of the Senkaku Islands in the East China Sea. Japan, a key U.S. ally, currently administers the islands; China is attempting to wrest them away. The United States (and Japan) may prefer to see China back down, but this issue is not important enough for Washington to justify the steep costs of nuclear use. America’s nuclear arsenal, therefore, will not be much help in forcing China to relinquish claims to disputed territory.

Trump might argue that he can make seemingly unbelievable nuclear threats credible by embracing unpredictability. In a 2016 speech, he declared, “We have to be unpredictable. And we have to be unpredictable starting now.” By cultivating a reputation as a rash “madman,” Trump may hope to extract concessions from U.S. adversaries with greater ease. There is just one problem with the madman theory of diplomacy: It doesn’t work.

Richard Nixon’s experiences as president are telling. Like Trump, Nixon embraced unpredictability, believing that this gave him advantages in international bargaining. In 1969, Nixon attempted to bring the Vietnam War to an end by raising the possibility of nuclear escalation. The president instructed his chief of staff, H.R. Haldeman, to tell the North Vietnamese, “We can’t restrain him [Nixon] when he’s angry — and he has his hand on the nuclear button.’” And so, Nixon predicted, “Ho Chi Minh himself will be in Paris in two days begging for peace.” The president went so far as to increase the readiness of U.S. strategic nuclear forces. But his gambit failed: The North Vietnamese were not intimidated, and U.S. involvement in the war persisted for four more years.

Nuclear weapons are by no means irrelevant. Having a nuclear arsenal makes the United States much less vulnerable to attack. Because defending the homeland is a vital national interest, it is much easier to make deterrent nuclear threats credible. But nuclear forces, regardless of their quantity and sophistication, will not help Washington negotiate better deals or extract concessions from enemies with greater ease. Increasing the size of the American nuclear arsenal is not a recipe for aiding U.S. coercive diplomacy.