It might be wise for the United States to resign itself to Iran's development of nuclear weapons and to focus on deterring the Islamic Republic from ever using them. But U.S. leaders have explicitly rejected that course of action. "Make no mistake: a nuclear-armed Iran is not a challenge that can be contained," U.S. President Barack Obama told the UN General Assembly last September. "And that's why the United States will do what we must to prevent Iran from obtaining a nuclear weapon." U.S. officials have also made it clear that they consider direct military action to prevent Iran from acquiring a nuclear weapon an extremely unattractive option, one to be implemented only as a regrettable last resort.

In practice, then, that leaves only two tools for dealing with Iran's advancing nuclear program: threats and promises, the melding of which the political scientist Alexander George labeled "coercive diplomacy." To succeed in halting Iran's progress toward a bomb, the United States will have to combine the two, not simply alternate between them. It must make credible promises and credible threats simultaneously -- an exceedingly difficult trick to pull off. And in this particular case, the difficulty is compounded by a number of other factors: the long history of intense mutual mistrust between the two countries; the U.S. alliance with Iran's archenemy, Israel; and the opacity of Iranian decision-making.

The odds of overcoming all these obstacles are long. If Washington truly wants to avoid both deterrence and military action, therefore, it will need to up its game and take an unusually smart and bold approach to negotiations.


The United States' recent record of coercive diplomacy is not encouraging. A combination of sanctions, inspections, and threats led Iraqi President Saddam Hussein to freeze his weapons of mass destruction program after the Gulf War, but it did not coerce him into accepting a long-term agreement. The reasons, as researchers have learned since Saddam's ouster, had to do with his motives and perceptions. The Iraqi leader not only sought regional dominance and the destruction of Israel but also worried about appearing weak to Iran, saw his survival in the wake of the Gulf War as a victory, and was so suspicious of the United States that a real rapprochement was never within reach. All this rendered ineffective the threats issued by the George W. Bush administration during the run-up to the 2003 U.S. invasion of Iraq and would likely have made promises of a reasonable settlement ineffective as well.

The Iraq case, moreover, is less an exception than the norm. Coercive diplomacy has worked on a few occasions, such as in 2003, when the Libyan leader Muammar al-Qaddafi chose to stop developing weapons of mass destruction partly as a result of pressure and reassurances from the United States. More often than not, however, in recent decades the United States has failed at coercive diplomacy even though it has had overwhelming power and has made it clear that it will use force if necessary. A succession of relatively weak adversaries, including Panama (1989), Iraq (1990 and 2003), Serbia (1998), and Taliban-ruled Afghanistan (2001), did not respond to American attempts at pressure, leading Washington to fall back repeatedly on direct military action. Coercive diplomacy did convince the military junta that ruled Haiti to step down in 1994, but only once it was clear that U.S. warplanes were already in the air. And today, Iran is hardly alone in its defiance: despite issuing many threats and promises, the United States has been unable to persuade North Korea to relinquish its nuclear arsenal or even refrain from sharing its nuclear expertise with other countries (as it apparently did with Syria).

The threats and promises the United States has used with Iran are not inherently incompatible: Washington has said it will punish Tehran for proceeding with its nuclear program but is willing to cut a deal with it should the program be halted. Logically, these components could reinforce each other, as the former pushes and the latter pulls Iran toward an agreement. But the dreary history of coercive diplomacy shows that all too often, threats and promises undercut, rather than complement, each other. 

Threats can prove particularly troublesome, since if they fail, they can drive the threatening party onto a path it may not actually want to follow. U.S. President John F. Kennedy learned this lesson during the 1962 Cuban missile crisis. Kennedy was mostly, but not completely, joking when he said, on learning that the Soviet Union had stationed warheads in Cuba, "Last month I said we weren't going to [allow it]. Last month I should have said we don't care." More important, ramping up threats can undermine the chances that promises will be taken seriously. Inflicting increasing pain and making explicit threats to continue to do so can also raise questions about whether the party inflicting the pain really wants a deal and raise the domestic costs to the suffering government of making concessions.

When the United States suggests that it is willing to bomb Iran if it does not negotiate away its weapons program, it implies that the Americans believe that the costs of military action are tolerable. Although this increases the credibility of the threat, it could also lead Iran to conclude that the United States sees the costs of bombing as low enough to make military action more attractive than any outcome short of a complete Iranian surrender. Moreover, because Iran's nuclear program is at least in part driven by the Islamic Republic's desire to be able to protect itself against attack, this U.S. threat is likely to heighten the perceived danger and so increase Iran's determination not to be swayed from its current course.

This does not mean that pressure is always counterproductive. According to U.S. intelligence agencies, the Iranians halted their development of nuclear weapons in 2003, presumably in response to the menace created by the U.S. invasion of Iraq. It appears that what a U.S. diplomat once said of North Korea also applies to Iran today: "The North Koreans do not respond to pressure. But without pressure they do not respond."


Even if pressure can work, and despite the fact that threats do not need to be completely credible in order to be effective, Washington faces daunting obstacles in trying to establish the credibility of its threat to strike Iran. What is most obvious, bombing would be very costly for the Americans (which is one of the reasons why it has not yet been done). As Tehran surely understands, Washington knows that the likely results include at least a small war in the region, deepening hostility to the United States around the world, increased domestic support for the Iranian regime, legitimation of the Iranian nuclear weapons program, and the need to strike again if Iran reconstitutes it. Given such high costs, Tehran might conclude that Washington's threat to bomb is just a bluff, and one it is willing to call.

Ironically, the success of economic sanctions could further diminish the credibility of the U.S. threat of a military strike. Iranian leaders might judge that their U.S. counterparts will continue to stick with sanctions in the hopes that the pain will ultimately yield a change in Iranian policy, or they might think that U.S. officials will hold off on the unpopular and unilateral military option to avoid disrupting the relatively popular and multilateral sanctions regime.

The credibility of Washington's threat to bomb is also affected by the perceptions and intentions of Iran's rulers. Iranian leaders might fall into the trap of basing their predictions about U.S. policy on their own expectations, which might differ from the Americans'. Those Iranians with relatively benign intentions toward the United States might expect that it would be fairly easy for the Americans to live with a nuclear-armed Iran, assume their U.S. counterparts will think similarly, and thus think a preventive U.S. military strike is unlikely. More aggressive Iranian leaders, on the other hand, might take the U.S. threat to bomb more seriously, since they themselves see Iran's acquisition of a bomb to be significant and assume their American counterparts will, too. These Iranian hawks might thus see U.S. preventive military action as plausible and expect it, moreover, to be aimed at broader goals, such as regime change, rather than simply setting back the Iranian nuclear program.

The history of U.S. policy toward Iran over the past decade will also complicate the credibility of American threats. On the one hand, the United States has imposed unilateral sanctions and skillfully mustered support from the Europeans for severe international sanctions. Many Western observers were surprised by this, and the Iranian leadership probably was, too. On the other hand, the United States has not bombed Iran despite continuing Iranian defiance of UN resolutions and U.S. policies. Iran also cannot have failed to notice that the United States did not attack North Korea as it developed its nuclear weapons, even after having repeatedly issued strong threats that it would do so. Moreover, Washington has been trying to coerce Iran into giving up its nuclear program for ages now, to little avail, making it hard to instill a sense of urgency in its current efforts.

Of course, threatening to bomb Iran's nuclear facilities is not the only form of pressure the United States can exert. Washington can maintain the current punishing sanctions regime indefinitely or even strengthen it. It could conduct additional covert actions, especially cyberattacks, to slow down the Iranian nuclear program. Because these actions are less costly to pursue than a military strike, threatening them might be more credible. But it can be more difficult to make such threats effective. The Iranians understand that they will pay a price for moving forward on the nuclear front. To change their minds, therefore, outsiders will have to threaten or inflict even greater pain than the Iranians are expecting.


There are various ways the United States can make its threats more credible. The first is to voice them publicly and unambiguously. Obama has already gone quite far in his public statements, so the low-hanging fruit in this area has been picked. If the confrontation continues, however, a concerted campaign to inform the American public about the impending risk of war would resonate strongly, especially if capped by a congressional resolution authorizing the possible use of force against Iran. If those steps failed to sway the Iranians, the United States could issue an ultimatum, sending a clear signal to all parties that time was running out for a peaceful solution to the crisis, although doing so would be highly controversial at home and abroad and would mean giving up the military advantages of surprise.

U.S. policymakers could also stop publicly expressing their reluctance to use force and instead emphasize that they think an attack on Iran would benefit the United States. They could claim to expect that a U.S. strike would deal a dramatic blow to Iran's nuclear effort, serve as a powerful warning to other potential proliferators, strengthen the United States' global reputation for resolve, and possibly even trigger an Iranian revolution.

Private threats at this point would probably add little, but threats delivered confidentially by third parties close to Tehran, such as China and Russia, might have more credibility, and these states might carry the message if they were convinced that the only alternative was U.S. military action. Conversely, Israeli statements expressing skepticism that the United States will ever bomb Iran have undercut Washington's position. If Israeli leaders were to stop such talk and start claiming that they are now confident that the United States is willing to strike if necessary (albeit not on the timetable that Israel would prefer), such a shift would be duly noted in Tehran.

The United States could also increase the credibility of its threats by specifying the Iranian actions that would trigger an attack. The fact that Obama has resisted calls to announce such "redlines" does not mean that he does not have them. It seems likely that the decision for a strike would be made if Iran got close enough to producing a nuclear weapon that it could do so quickly and stealthily, or began producing highly enriched uranium, or expelled the International Atomic Energy Agency's inspectors. Still, even if announcing specific redlines such as these would enhance U.S. credibility, it would have downsides as well. Specifying what would be prohibited would mark out what would be permitted, and Iran could take that as an invitation to move right up to the redlines.

Washington could lend its threats credibility through actions even more than through words. It could bolster its military capabilities in a way that demonstrated its seriousness, including making expensive preparations to deal with retaliation by Iran after an American attack. It could even begin military maneuvers that have some risk of provoking Iran and leading to escalation, thus showing that Washington is not frightened by the prospect of a fight developing accidentally.

U.S. threats could also be made more credible if Washington developed plans for a strike against Iranian nuclear facilities and then deliberately allowed Iranian intelligence services to learn the details. In this scenario, the Iranians would have to believe they discovered something the Americans had sought to hide from them, lest they conclude it was simply a ruse designed to impress them. This kind of maneuver is tricky: although sound in principle, in practice it has generally proved too clever by half. During the 1961 Berlin crisis, for example, the Kennedy administration provided West Germany with its plans for a military response to the standoff, knowing the West German government had been penetrated by Soviet intelligence. And in 1969, the Nixon administration staged an ostensibly secret nuclear-alert exercise designed to convey the strength of the U.S. commitment to South Vietnam. In both cases, however, the Soviets hardly noticed.

One might assume that the United States could increase the credibility of its threats in Iranian eyes by building up its defenses, seemingly in preparation for a possible conflict. But bulking up U.S. capabilities against Iranian missiles in the eastern Mediterranean and the Persian Gulf might also send the opposite signal -- that the United States is preparing not to attack but rather to live with (and deter) a nuclear-armed Iran. Canceling the deployment of systems designed to defend against Iranian missiles, in fact, would be a strong and dramatic signal that the United States has no intention of allowing a nuclear Iran and is willing to strike preventively to head off such a prospect.


In general, making promises credible is even harder than making threats credible, and that is especially true in this case because of the history of mutual mistrust and the conflicting historical narratives that each side tells itself. U.S. promises to Iran are complicated by other factors as well. There are multiple audiences listening in on anything Washington says to Tehran: domestic constituencies, Arab states, North Korea, other states that might seek nuclear weapons, and, of course, Israel. The fear of an Israeli attack may provide a useful source of extra pressure, but Iranian perceptions of U.S.-Israeli collusion can make U.S. signaling to Iran more difficult. American promises must be seen to cover Israeli actions as well, and some promises designed to reassure Israel of U.S. protection might conflict with conciliatory messages Washington wishes to send to Tehran.

U.S. policymakers also have limited knowledge of Iranian perceptions and domestic politics. It is generally agreed that Iran's nuclear policy rests in the hands of the country's supreme leader, Ayatollah Ali Khamenei. But it is hard to know just what his goals are, how he perceives U.S. messages, and even which messages are accurately conveyed to him. If history is any lesson, the likelihood is that he interprets much American behavior, including promises, in ways that Americans would find utterly bizarre.

Just what various Iranian actors would perceive as a reward, moreover, might be hard to determine. Some figures in or close to the regime, for example, have built fortunes and political power bases around adapting to sanctions, so removing or loosening sanctions might actually harm rather than help them. Even the most valuable prize the West could offer -- the normalization of relations and the integration of the Islamic Republic into the world community -- could conflict with the worldview of dominant actors in Iran, undercut their power, and be seen by them, quite possibly accurately, as a step toward eventual regime change.

All these gaps in knowledge and trust stand in the way of the United States' ability to make credible promises of any kind to Iran, whether minor assurances intended to serve as confidence-building measures or the more substantial promises that could lead to a durable diplomatic settlement. In the most likely deal, Iran would agree to stop designing warheads and to refrain from enriching uranium above the 20 percent level. It would retain only limited stockpiles of uranium enriched to 5–20 percent, accept limits on the capacities of its enrichment facilities, allow robust inspections of its nuclear facilities, and agree to refrain from building facilities that the United States could not destroy. (Such a deal would permit the heavily fortified underground Fordow enrichment plant to remain open, since it is vulnerable to a U.S. strike -- something that would displease the Israelis, whose own capabilities are insufficient to overcome Fordow's defenses.)

In return, the United States would accept a limited Iranian enrichment program, promise not to try to overthrow the regime (and maybe not to undermine it), and suspend sanctions that were imposed specifically in response to the nuclear program. The United States might also restore normal diplomatic relations with Iran -- although taking that step, along with lifting other sanctions, might require a larger grand bargain involving Iran's ending its support for Hamas and Hezbollah.

To convince Iran that such a deal is possible, the United States would have to surmount four barriers. It would need to gain some measure of Israeli acquiescence, both to satisfy influential pro-Israel constituencies in the United States and to convince Iran that the deal would not be undercut by Israeli sabotage, assassinations, or attacks. Accepting a civilian nuclear program in Iran would necessitate repealing or carving out some sort of exception to various UN Security Council resolutions, because the original sanctions were applied in response to the establishment of the nuclear program itself, not to the subsequent progress Iran has apparently made.

Washington would need to convince Tehran that negotiations were not designed to weaken it and that a settlement would end American efforts at regime change. Security assurances would have to be part of any deal, and they would be hard to craft. The fact that the United States helped overthrow Qaddafi in 2011 despite his earlier agreement to abandon his weapons of mass destruction program would surely be on Iranian minds.

Finally, the United States would have to find some way of offering Iran intangible goods it truly craves: respect and treatment as an equal. Not only can the process of hard bargaining get in the way of respectful treatment, but so can even the imagery used to think about such bargaining -- such as talk of "carrots and sticks," which implies that Iran is an animal that the West is trying to manipulate. On the other hand, showing respect to Iran would not cost the United States a great deal.


Although the United States and its European allies are talking with Iran now, these conversations seem to involve little more than recitations of unyielding opening positions. Distrust is often highest at the beginning of a negotiation process, since both sides fear that any preliminary concessions will not only be pocketed but also be taken as a sign of weakness that will embolden the other side to hold out for more.

There are standard, if imperfect, ways to deal with this problem, such as by using disavowable third parties who can float enticing ideas without exposing actual negotiating positions. Ambiguous "feelers" are also useful, since they require the other side to respond to a message before its true meaning is revealed and so limit the first state's exposure. But the distrust between the United States and Iran runs so deep that the normal playbook is unlikely to work here. Getting through to the supreme leader and convincing him that serious negotiations are in his interest will be difficult. Appealing to him personally and directly, in both public and private, might be effective, as might sending a high-level emissary (although such steps should be reserved until close to the last possible minute, to avoid undue humiliation should they fail).

A dramatic (if unlikely) approach would be for the United States to unilaterally suspend some of its sanctions against Iran, halt all its military preparations related to Iran, or declare that the option of using force is no longer on the table. A more plausible scenario would be for U.S. leaders to try to communicate that they are ready for an agreement by letting the Iranian regime know that they are studying how to suspend sanctions in stages and developing various forms of security guarantees.

The normal negotiating procedure would be to start with small confidence-building measures and put off dealing with the central and most difficult issues for while, until some progress and mutual trust have been achieved. It is probably too late for that, however, especially since many of the standard smaller steps have been removed from consideration by the recent application of even tougher international sanctions on Iran. Until recently, for example, a freeze-for-freeze approach to confidence building might have been possible: a U.S. offer to take no further aggressive steps in exchange for a comparable Iranian move. But at this point, given the pain the sanctions are currently inflicting, modifying them or suspending them would probably be required, which would be a much bigger concession on the part of the United States and Europe.

It will probably be necessary for Washington to sketch the broad contours of a possible final agreement before talks begin. Entering serious negotiations would carry high political costs for the White House and spark a major political struggle in Tehran -- risks the leaders on each side would take only if there seemed to be good prospects of an acceptable solution. And any agreement, of course, would have to be carried out incrementally in order for each side to guard against the other's reneging.

Still, the United States may need to put more of its cards on the table at the start. It will have to convince Khamenei that successful negotiations would greatly reduce the threat to his country posed by the United States and that Washington would be willing to accept an appropriately safeguarded Iranian civilian nuclear program. There will be a strong temptation in Washington to reserve such inducements for the final stage of hard bargaining, but holding them back is likely to greatly decrease the chance that the negotiations will reach that stage at all.

The obstacles to successful negotiations may be so great that the best the United States can achieve is a form of containment that would maintain something like the status quo, with Iran remaining at some distance from a weapon. Such a situation might not be stable, however, and what Soviet Premier Nikita Khrushchev told Kennedy at the height of the Cuban missile crisis could also prove relevant to the U.S.-Iranian confrontation: "Mr. President, we and you ought not now to pull on the end of the rope in which you have tied the knot of war, because the more the two of us pull, the tighter the knot will be tied. And a moment may come when that knot will be tied so tight that even he who tied it will not have the strength to untie it. And then it will be necessary to cut that knot."

Looking carefully at the challenges of coercive diplomacy in this case is sobering. Using threats and promises to successfully manage the problems posed by Iran's nuclear program will be difficult at best, requiring extraordinary levels of calmness, boldness, creativity, and forbearance. But if Washington is determined to avoid both military action and deterrence, those are the qualities it will need to summon.

You are reading a free article.

Subscribe to Foreign Affairs to get unlimited access.

  • Paywall-free reading of new articles and a century of archives
  • Unlock access to iOS/Android apps to save editions for offline reading
  • Six issues a year in print, online, and audio editions
Subscribe Now
  • ROBERT JERVIS is Adlai E. Stevenson Professor of International Politics at Columbia University and a member of the Saltzman Institute of War and Peace Studies.
  • More By Robert Jervis