
Throughout the nuclear era, the conventional wisdom has been that one state’s nuclear acquisition has driven its adversaries to follow suit. As former Secretary of State George Shultz so eloquently put it, “proliferation begets proliferation.”

Although some of the earliest nuclear proliferation cases followed this pattern, it has been increasingly rare as the taboo against the first use of nuclear weapons has become more entrenched. Instead, the primary security factor driving nuclear weapons proliferation today is the disparity in conventional military power. This is likely to continue in the future, with profound consequences for which states do and don’t seek nuclear weapons.

Although conventional military power’s importance in nuclear proliferation has certainly increased in recent decades, it wasn’t completely negligible in earlier years. France’s pursuit of a nuclear weapon is a case in point. The historical narrative on France’s nuclear program has been that it was motivated by Charles De Gaulle’s intense nationalism and lack of faith in extended deterrence.

The archival record does not completely support this interpretation, however. To begin with, as Jacques Hymans finds from his careful review of the historical record, it was Mendes France not De Gaulle who made the first crucial decisions to pursue the bomb. The timing of President France’s decision is telling; specifically, he ordered the initial preparations be made for building an atomic weapon three days after the Nine-Power Conference laid out the terms for West Germany’s rearmament, largely over Paris’s objections.

President France’s rationale was straight forward. As Hymans explains, he believed that “French military power must remain at least one order of magnitude superior to Germany’s; thus, the fewer the restrictions on German conventional weapons, the greater the need for a French atomic force.” Given France’s suffering at the hands of the German military in WWI and WWII, his decision isn’t too hard to comprehend.

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Israel’s decision to pursue the bomb was also motivated almost entirely by its perceived conventional inferiority vis-à-vis its Arab neighbors. Although these neighbors did not possess nuclear weapons, Israeli leaders in the late 1950s and 1960s could not be optimistic about the military balance both then and into the future. After all, Egypt alone is 55 times larger than Israel and, in 1967, had about eleven times its population. Israeli leaders therefore calculated that acquiring a nuclear weapon was the surest way to negate this inherent conventional imbalance, and thereby ensure the Jewish state’s survival.

As the nuclear taboo has become more entrenched over the decades, states have had less to fear from a neighbor acquiring an atomic weapon. Consequentially, conventional military power has surpassed nuclear arsenals in terms of its importance in driving nuclear proliferation.

North Korea illustrates this nicely. Although Pyongyang began its nuclear program during the Cold War, it only started making substantial progress in the late 1980s and early 1990s. Notably, this was when the nuclear threat it faced was declining as the U.S. withdrew its nuclear weapons from South Korea.


By contrast, it was also the time when North Korea had the most to fear from the conventional military balance on the Peninsula. Not only had it lost its great power protectorate in the Soviet Union, but South Korea’s economic ascendancy, combined with its inherent demographic advantage, meant that Pyongyang’s military position was growing precarious even if America was not part of the equation.

Of course, the U.S. military is part of the equation on the Korean Peninsula, and its stunning victory in the first Gulf War left little doubt about its conventional dominance in the post-Cold War era. Subsequent years have confirmed this dominance, as well as the United States’ willingness to use it to overthrow adversarial governments. This was ominous indeed for policymakers in Pyongyang, who rightly calculated that they couldn’t match America’s conventional military might. Consequently, they sought to negate its military superiority by acquiring the ultimate deterrent.

The Islamic Republic of Iran’s nuclear program has followed a similar trajectory. Although the initial decision to restart the Shah’s nuclear program was motivated almost entirely by Saddam Hussein’s nuclear and chemical weapons programs, Tehran only began making real progress on the nuclear front in the middle to late 1990s. Saddam Hussein can hardly explain this trajectory, given that his threat to Iran was significantly diminished following the first Gulf War, and it was eliminated entirely after 2003.

Iran’s nuclear program is better explained, then, by the rise in the potential conventional threat the U.S. poses to Iran. In the post-Cold War era, this began in full force when the U.S. decided to reactivate the 5th Fleet in July 1995, after a 45-year hiatus. Suddenly, U.S. Naval might was permanently stationed on Iranian shores.

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Further underscoring this danger to Iran, the following year President Bill Clinton signed the Iran and Libya Sanctions Act of 1996, confirming that President Akbar Hashemi Rafsanjani’s outreach to the U.S. had failed. The U.S. threat to Iran has only grown more precarious since 2003; not surprisingly, Iran’s nuclear program has made its greatest advances during this time.

The conventional military balance’s primacy in influencing horizontal nuclear proliferation is also evident from the states that have not chosen to go nuclear. For instance, no Northeast Asian country went nuclear following China or North Korea’s nuclear tests, nor did Israel’s nuclear arsenal cause a nuclear arms race in the Middle East.

The fact that conventional military power is the strongest factor driving nuclear proliferation should guide how we think about proliferation threats in the future. For instance, if Iran acquires nuclear weapons, its neighbors will be unlikely to follow suit. Not only do these states lack the necessary technical capacity, but they have little to fear from Iran’s nearly non-existent power projection capabilities.

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On the other hand, the rise in China’s conventional military strength makes it likely that Eastern Asia will be the region where the most potent proliferation risks emanate from. Countries with territorial disputes with China—first and foremost, Japan— will have the strongest motivation to build the bomb. Unfortunately, for non-proliferation advocates, many of China’s neighbors—including Japan and South Korea— already have robust civilian nuclear programs. This breakout capability will only make it more tempting for policymakers to order a mad dash for the bomb.