Nuclear weapons won't necessarily make Iran more aggressive

Nevertheless, one can overstate both the probability and the effectiveness of blackmail. It is again useful to recall that analysts expressed similar fears about China when it acquired nuclear weapons, yet Beijing's behavior for the most part did not validate those fears. Although China did attack Vietnam in 1979, the PRC's conduct since the late 1960s has generally been less, rather than more, bellicose than it was when China lacked a nuclear capability. That episode illustrates the larger point that nuclear weapons are much more useful as a deterrent against possible adversaries than they are as a mechanism for intimidating those adversaries, much less for war-fighting purposes. There are indications over the past several years that the two newest nuclear powers, India and Pakistan, have reached that conclusion. As in the case of China after the 1960s, New Delhi and Islamabad appear to have become more cautious and restrained since they built nuclear arsenals. One cannot guarantee that Tehran would follow that pattern, but by the same token it is unwarranted to assume that the Iranian regime would engage in rampant blackmail.

Notwithstanding these considerations, it is important not to overestimate the utility of nuclear weapons. To date, nation-states have not found them to be useful as instruments of overt military aggression. While the possession of nuclear weapons may allow North Korea and Iran to pursue more vigorously objectives that run counter to U.S. interests, it seems likely that these adversaries will do this in a constrained fashion. In fact, we have no historical cases in which an emerging nuclear power undertook large-scale military aggression to advance revisionist claims. So we do not foresee a nuclear-armed North Korea becoming likelier to invade South Korea. Nor do we expect that Iran would use nuclear weapons, should it acquire them, as a shield to facilitate large-scale conventional aggression against Saudi Arabia, the Persian Gulf states, or adversaries further afield, including Israel.

A close look at the history of the nuclear age shows that countries with nuclear weapons are neither more likely to make coercive threats nor more likely to succeed in blackmailing their adversaries. Nuclear powers such as the United States and the Soviet Union certainly made numerous threats after they acquired nuclear weapons. But so did Libya, Serbia, Turkey, Iraq, Venezuela, and dozens of other countries that did not possess the bomb. Nuclear weapons are not a prerequisite for engaging in military blackmail. Further, there is scant evidence that possessing the bomb makes coercive threats more successful when they are made. Nuclear weapons did not help the United States compel North Korea to release the USS Pueblo and its crew in 1968. Israeli coercive threats backed by the implicit threat of nuclear war failed against Syria prior to the 1982 Lebanon War, just as British threats against Argentina in 1982 were unable to compel the return of the Falkland Islands, despite Britain’s possession of nuclear weapons.

The Pakistani-Indian conflict may be such a situation. Pakistan’s nuclear arsenal may have enabled it to engage in riskier behavior in Kashmir than it otherwise would attempt, because nuclear weapons help to deter Pakistan’s ultimate nightmare: an assault by the militarily superior India, which could slice Pakistan in two and perhaps destroy it completely. But if you try to apply that logic to Iran, no one is playing the role of India. Iran has its own tensions and rivalries with its neighbors— including Iraq, Saudi Arabia, other states on the Persian Gulf, and Pakistan. But none of these pose the kind of existential threat that Pakistan sees coming from India. Moreover, none of the current disputes between Iran and its neighbors (such as the one over ownership of some small islands also claimed by the United Arab Emirates) come close to possessing the nation-defining significance that the Kashmir conflict poses for both Pakistan and India.