The force needed to contain Iran

As Iran relentlessly moves toward acquiring a nuclear weapons capability, calls will grow for the United States to think seriously about how to contain Tehran. A preventive attack will not work, some will argue, and could unleash a wave of terrorism that would further imperil Iraq and Afghanistan. Conversely, containment will be held up as a way to deter Tehran without having to resort to military force.

But this view draws a false distinction between containment and force. A preventive attack might not end Iran's nuclear ambitions. Defense Secretary Robert Gates argues that a successful attack would delay the Iranian program by at most a few years. Yet a policy of containment will not save the White House from having to make tough choices about using force. Indeed, Iran can be contained only if Washington is prepared to use force against an emboldened adversary armed with the ultimate weapon.

The rationale for the Iranian nuclear program has changed over time. It began as part of a largely defensive strategy under the moderate presidencies of Ali Akbar Hashemi Rafsanjani and Mohammad Khatami. Nuclear weapons would provide a way to deter a range of foes while enhancing national prestige.

Today, as Iranian hawks consolidate their power and the Revolutionary Guards emerge as a key pillar of the state, Tehran views nuclear weapons as the means to regional preeminence. A nuclear shield would give Iran freedom to project its power in the Middle East. Such an Iran is unlikely to be subtle about brandishing the nuclear card.

It would take considerable American political skill and will to contain such regional pretensions. Washington would need to be explicit about its red lines: no initiation of conventional warfare against other countries; no use or transfer of nuclear weapons, material or technologies; no stepped-up support for terrorist or subversive activities. Washington would need to be just as explicit about the consequences of crossing those lines: potential U.S. military retaliation by any and all means necessary.

Tehran would probably test U.S. resolve early on, believing that regional dynamics had shifted sharply in its favor. In that case, the United States would face a momentous credibility crisis because it had failed to stop Iran from going nuclear after persistently declaring that such an outcome was unacceptable. Even close U.S. allies would doubt Washington's security guarantees.

An emboldened Iran would test Washington in several ways. It would probably lend more support to Hezbollah and Hamas and encourage them to act more aggressively against Israel. It might step up subversive activities against the Gulf sheikdoms and demand that they evict U.S. troops from their territory.

A nuclear Iran could also be tempted to transfer nuclear materials and technologies to other countries. President Mahmoud Ahmadinejad has already declared that "Iran's nuclear achievements belong to all those countries thinking of peace and welfare, and we are prepared to provide these achievements to those who hate war and aggression." How would the United States respond to an Iran that transferred advanced centrifuges or nuclear weapon designs to its Syrian ally? Or if it gave fissile material to a terrorist group?

Such dangerous and destabilizing actions cannot be addressed by tough diplomatic talk or yet more U.N. Security Council resolutions. It can be addressed only by a willingness to respond with force. And in the curious logic that governs deterrence, a Tehran that believes Washington will retaliate will be less likely to act aggressively in the first place.

The challenges of making containment work make it far preferable that Iran stop -- or be stopped -- short of becoming a nuclear power. Efforts to negotiate limits on Iran's nuclear program must be pursued with vigor, and economic pressure on Tehran must be maintained. Military options should not be taken off the table.

If Tehran remains determined to go nuclear and preventive attacks prove too risky or unworkable to carry out, the United States will need to formulate a strategy to contain Iran. In doing so, however, it would be a mistake to assume that containment would save the United States from the need to make tough choices about retaliation. If Washington is not prepared to back up a containment strategy with force, the damage created by Iran's going nuclear could become catastrophic.

James M. Lindsay, senior vice president and Ray Takeyh, a senior fellow at the Council on Foreign Relations. Their article "After Iran Gets the Bomb" will be published in the March-April issue of Foreign Affairs.