Although it is possible that negotiations between the leading powers in the international community and Iran may produce a settlement to the vexing issue of Iran's nuclear program, it is more likely that those negotiations will fail. If that happens, U.S. policymakers face a set of highly imperfect options.
One option—and the most likely initial response—is to seek a UN Security Council resolution imposing economic sanctions on Tehran. However, sanctions have a poor record of getting regimes to abandon high-priority policies. Even if Russia and China can be induced to overcome their reluctance to endorse sanctions, it is unlikely that such measures would halt Iran's quest for nuclear weapons.
A second option is to intensify efforts to subvert Iran's clerical regime. Washington already has a modest program to do that under the Iran Freedom Support Act. Unfortunately, such a strategy may backfire, undermining the domestic legitimacy of Iranian dissidents. Moreover, there is no certainty that a democratic Iran would choose to be nonnuclear.
Option three is to launch preemptive airstrikes against Iran's nuclear installations. That is the most unwise strategy. At most, such strikes would delay, not eliminate, Tehran's program. There is also a grave risk that Iran would retaliate with the full range of options at its disposal, including attacks against U.S. forces in Iraq and through proxy organizations. Attacking Iran would also further alienate Muslim populations around the world, creating the very real prospect of a war of civilizations.
Option four is to reluctantly accept Iran as a member of the global nuclear weapons club and rely on the deterrent power of America's vast nuclear arsenal. While that strategy is not without risk, the United States has successfully deterred other volatile and unsavory regimes, most notably Maoist China during that country's Cultural Revolution.
The best option, though, is to try to strike a grand bargain with Iran. Washington should offer to normalize diplomatic and economic relations with Iran in exchange for Tehran's agreement to open its nuclear program to rigorous, on-demand international inspections to guarantee that there is no diversion of nuclear material from peaceful purposes to building weapons.