Last Chance for Iran

History counsels skepticism toward Iran's newly rediscovered willingness to negotiate. Western diplomats have often walked away from such talks empty-handed. We believe, however, that the Oct. 1 talks present an important opportunity to reveal Tehran's intentions and for President Obama to convince other nations of the need for biting sanctions. They must be taken seriously.

Secretary of State Hillary Rodham Clinton has said that the objective of this latest round of talks should be "to meet and explain to the Iranians, face to face, the choices that Iran has." Tehran has time and again made the same unfortunate choice: to use the promise of diplomatic engagement to delay and discourage international pressure.

We have little time left to expend on Iranian stalling tactics, if that is indeed what this overture is. As we noted in a report for the Bipartisan Policy Center last week, which was based on an in-depth study of Iran's known enrichment capacities and uranium stockpile by a respected nuclear power expert, we believe Iran will be able to produce a nuclear weapon by 2010. Meanwhile, Israel appears ever more determined to conduct a unilateral military strike if necessary.

If diplomacy is to succeed, the United States cannot allow Iran to dictate the terms of engagement. Agreeing on a realistic strategy with our partners is at least as important as what is said around the negotiating table. As we have argued in earlier reports and on this page, successful diplomacy with Iran requires first "laying a strong strategic foundation" of alliance- and leverage-building. So long as Iran has not suspended its enrichment activities, the United States and its partners should limit negotiations to a specific time frame. If credible progress is not made in that time, we must be prepared to walk away from the negotiating table. Otherwise, Tehran will be able to drag out the talks endlessly while its centrifuges continue to spin.

Another key condition for successful negotiations is building leverage on Iran. Ideally, during the Group of 20 summit this week and the time before the talks, there could be a push for expanded sanctions targeted at Iran's financial and energy sectors, as well as at foreign companies that do business with them. By ratcheting up pressure on Iran before we sit down, Western negotiators would gain both sticks (additional measures) and carrots (repealing sanctions) with which to induce Iranian cooperation.

There is, unfortunately, little international appetite for tougher sanctions. French President Nicolas Sarkozy's strong statement on Wednesday notwithstanding, European support is not universal. Also, Russia has rejected sanctions outright, while China is intent on increasing its commercial and energy ties to Iran.

Thus President Obama's primary objective during and after negotiations must be marshaling international support for more robust sanctions. Although the circumstances are not yet clear, we hope that the administration's recent decision to shelve planned missile defense deployments in Poland and the Czech Republic is tied to Russian concessions on Iran; if not, this could significantly undermine our leverage with Russia as well as Iran.

U.S. participation in the October talks will further demonstrate its commitment to diplomacy and build additional global goodwill. If it becomes evident that these talks will end as have all past negotiations -- fruitlessly -- the limitations of engagement, and the need for tougher measures, will be hard to deny. We must not mistake process for progress.

Should the international community fail to support sanctions even in those circumstances, there is still much that United States can do to pressure Tehran. It could conduct overt military preparations, such as sending an additional carrier battle group to the Persian Gulf or holding military exercises in the region. This should demonstrate to Tehran the costs of continued defiance and persuade European leaders that they make armed conflict more likely by refusing to adopt tougher measures.

If all else fails, in early 2010, the White House should elevate consideration of the military option. This need not involve a strike. A naval blockade would help ensure the effectiveness of proposed sanctions, such as an embargo on gasoline imports. Ultimately, though, a U.S.-led military strike is a feasible, albeit risky, option of last resort.

Next month's talks may be one of the last opportunities to diplomatically address the advancing Iranian nuclear threat. If Iran chooses to waste yet another such chance, President Obama will have no choice but to fulfill his February commitment to "use all elements of American power to prevent Iran from developing a nuclear weapon."

Daniel R. Coats, a former Republican senator from Indiana; Charles S. Robb, a former Democratic senator from Virginia and Charles Wald, a retired general and air commander in the initial stages of Operation Enduring Freedom. They are authors of the Bipartisan Policy Center report Meeting the Challenge: Time Is Running Out.