Even as other issues surrounding Iran’s nuclear program are debated, there is a wide-ranging consensus in the West that an Iranian bomb would precipitate a regional nuclear-arms race, if not a global one. Senators Lindsay Graham (R-SC), Robert Casey (D-PA) and Joseph Lieberman (I-CT) said as much in the pages of the Wall Street Journal in March. Similarly, British foreign secretary William Hague worries that if Iran acquires a nuclear weapon, “the most serious round of nuclear proliferation” to date would commence. And recently in the New York Times, Ari Shavit of Haaretz stated matter-of-factly that “an Iranian bomb will bring about universal nuclear proliferation.”

Fortunately for mankind’s sake, there is no evidence to support these apocalyptic prophecies. Although some precautionary actions might be prudent, neither history nor contemporary circumstances indicate that an Iranian atomic weapon would be a nuclear catalyst.

Historical Precedents

To begin with, fears of an impending nuclear tipping point have been a regular feature of the nuclear age. The CIA is a case in point. Whereas in 1957 the agency predicted ten countries could go nuclear within a decade, by 1975 it concluded that “logically” nuclear proliferation would only subside when “all political actors, state and non-state, are equipped with nuclear armaments.” A quarter century and one nuclear power later (both South Africa and Pakistan acquired a nuclear-weapons capability during this time, but South Africa dismantled all its nuclear weapons by 1991), CIA director George Tenet announced in 2003 that we had entered “a new world of proliferation” and warned “the ‘domino theory’ of the twenty-first century may well be nuclear.”

The 1960s were equally remarkable. As a presidential candidate in 1960, for example, John F. Kennedy foresaw “ten, fifteen, or twenty nations” acquiring a nuclear capability by the 1964 election. The following year, the Kennedy administration was so certain a Chinese nuclear test would trigger a global wave of nuclear proliferation that it considered simply giving Beijing’s neighbors “defensive nuclear weapons.” Although not a single additional nuclear power emerged by 1963, President Kennedy remained “haunted by the feeling” that there would be fifteen or twenty of them by 1975 and possibly twenty-five by the end of that decade.

And yet nearly half a century after the Cuban missile crisis there are only nine nuclear-weapon states, five more than when Kennedy was elected and two of which already had advanced nuclear weapon programs during his presidency. During the same time interval, four states have voluntarily given up their nuclear arsenals and an estimated forty nations have not built them despite possessing the technical capability to do so.

The Future of Proliferation

Still, just because nuclear forbearance has been the norm thus far doesn’t necessarily mean this will continue into the future. In fact, according to Shavit, an Iranian bomb would “force Saudi Arabia, Turkey and Egypt to acquire their own.” Similarly, President Barack Obama is “almost certain” that if Iran gets nuclear weapons, its neighbors will be “compelled” to do the same.

Once again, there’s not much evidence to support these assertions. Although a few countries have built nuclear weapons because a rival acquired them, these are the exceptions to the general rule. Of the quantitative studies done on reactive proliferation, none have found a nuclear-armed rival makes a state more likely to even initiate a nuclear-weapons program, much less succeed. Furthermore, as the political scientist Jacques Hymans documents in a forthcoming book, despite the diffusion of technology, nuclear aspirants have become increasingly inefficient and unsuccessful over time.

It’s therefore not surprising that in-depth case studies of Turkey’s, Egypt’s and Saudi Arabia's nuclear prospects have found no cause for concern. Turkey is the most capable of building nuclear weapons but already has a nuclear deterrent in the form of an estimated ninety nuclear warheads hosted on its territory for the United States. This is far more than what it is capable of producing indigenously. Additionally, it’s hard to square Turkey’s supposed nuclear ambitions with the recent removal of its entire stockpile of highly enriched uranium.

Egypt is far less capable of building a bomb than Turkey. Indeed, it already had a dysfunctional nuclear program during the 1960s that was abandoned despite Israel, its archenemy at the time, acquiring a nuclear capability. Even before the onset of the Arab Spring, proliferation analyst Jim Walsh argued it was “not likely that Egypt will seek, let alone acquire, nuclear weapons.” In the aftermath of Mubarak’s overthrow, any government in Cairo will be preoccupied with improving the lot of its people, lest it too wind up on trial. Achieving economic growth will require sustained access to foreign capital, markets and financial assistance, none of which would be forthcoming if Cairo initiated a nuclear-weapons program.

Given its long-standing rivalry with Tehran, Saudi Arabia is certainly the most alarmed by the prospect of a nuclear-armed Iran. Moreover, Saudi Prince Turki al-Faisal, former head of intelligence and ambassador to the United States and the United Kingdom, has repeatedly warned that if Iran is allowed to get nuclear weapons, the kingdom may well do the same. Of course, this might be what a nation would say if it wanted Washington to “cut off the head of the snake” in Tehran.

In fact, as Nuclear Threat Initiative concludes, “no convincing evidence exists . . . that Saudi Arabia is attempting to develop, or has the motivation to develop, a nuclear weapons program.” Similarly, in his comprehensive study that included fieldwork inside the kingdom, Ibrahim Al-Marashi found “little evidence . . . that Saudi Arabia would seek to engage directly in a regional nuclear arms race.”

If Saudi Arabia did pursue nuclear weapons, however, it would be almost certain to fail. Even those most concerned about a Saudi bomb don’t claim it can build one itself. Rather, they contend Riyadh will buy a ready-made nuclear deterrent from Pakistan. Pakistan’s willingness to take this unprecedented action is based on pure speculation, past Saudi aid to Pakistan and a host of unsubstantiated claims, most notably those made by Mohammed al-Khilewi, a Saudi diplomat at the UN who defected in 1994. In seeking to gain asylum into the United States, al-Khilewi told U.S. authorities that in exchange for financial aid, Pakistan had agreed to provide Riyadh with a nuclear deterrent should the need ever arise.

Besides al-Khilewi’s obvious motives for fabricating this story, it’s doubtful Islamabad would uphold its end of the alleged bargain. After all, in the wake of 9/11 Washington gave Islamabad $22 billion to fight terrorism and later found Osama bin Laden living amongst Pakistan’s military cadets. Furthermore, Pakistani leaders are exceedingly paranoid their nuclear arsenal would not withstand an Indian or U.S. first strike. It’s therefore difficult to imagine them willingly parting with any nuclear warheads.

Even if Islamabad did have some to spare, Riyadh would be an unlikely recipient. Given the world’s dependence on Saudi crude, Pakistan would be the target of exceptionally harsh and unrelenting international condemnation, including from its “all-weather friend” China, which has recently been getting 20 percent of its oil supplies from Riyadh. Iran would also be outraged and almost certain to respond by aligning itself squarely with India. Pakistani leaders have gone to great lengths to avoid this outcome, and they wouldn’t suddenly invite it just to keep a promise their predecessors might have made.

If Iran does acquire nuclear weapons, there’s no reason to think a regional nuclear-arms race would follow. Washington and its allies have avoided this outcome in the past, and nothing suggests this time would be different.

Zachary Keck is deputy editor of e-International Relations and an editorial assistant at The Diplomat. His commentary has appeared at Foreign Affairs, Foreign Policy, World Politics Review and Small Wars Journal.