Let's assume the Iranian nuclear talks in Vienna fail to conclude a final agreement by Nov. 24, the already extended deadline under the interim Joint Plan of Action signed in January. Iran's clerical regime has refused to give much ground in key areas, and the Obama administration has, so far, been unwilling to meet Iranian demands. If the White House doesn't end November with a cascade of concessions leading to a deal, there are four paths forward. None is appealing. Two might be effective—but the president is unlikely to choose either one.
The deadline is approaching with dwindling hope for a deal in part because Iran has already gotten so much that it wants. During the 2012 negotiations leading to the interim deal, the White House accommodated Supreme Leader Ali Khamenei 's red lines against reducing enrichment capacity and foreclosing an industrial-size program.
Iran thus got its wish to continue programs for uranium enrichment, long-range ballistic missiles and centrifuge development. Iran further refused to accept intrusive U.N. or other inspections, balked at dismantling the heavy-water reactor at Arak, and declined to discuss past weaponization research. It also won agreement that any restrictions on its nuclear program would be of limited duration. Tehran has treated the U.S. concessions to its demands as permanent—effectively making further diplomatic advances contingent on greater Western "flexibility."
Washington keeps trying to tiptoe around Mr. Khamenei's red lines. Take the recent American suggestion that Iran disconnect all "excess" centrifuges and cascade piping used in uranium enrichment at Iran's Natanz facility—and retire around 14,000 first-generation machines into storage under United Nations safeguards. That plan is likely a nonstarter: Mr. Khamenei has adamantly opposed any reduction in enrichment capacity.
If there is no final deal this month, other scenarios arise.
First: The White House could give up on diplomacy and pre-emptively strike Iran's nuclear sites. Although this option could seriously, even terminally, damage Tehran's nuclear program, it is highly unlikely. Mr. Obama is too cautious to do something so aggressive. His entire political agenda and moral philosophy on American disengagement from the Muslim Middle East would collapse after a bombing raid.
Second: The administration could give up on the current talks and default back to sanctions, but again trying to undercut their seriousness, as the president attempted to do in 2011 and 2012. Congress imposed the most economically painful measures—targeting Iran's oil exports, central bank and access to the Swift interbank system—over his objections. The president has always hoped that "rationality" would take hold in Tehran, that the regime would see the economic benefits that come with good behavior. The Islamic Republic has enjoyed an economic reprieve, thanks to Mr. Obama's decision last year to de-escalate sanctions pressure by blocking new congressional action and giving billions of dollars in direct sanctions relief as part of the interim deal.
Third: New, even more biting sanctions could be enacted, causing Tehran considerable pain. Current energy markets, with a declining price for crude, offer ample room for Congress to threaten sanctions against any country's central bank involved in buying Iran's oil exports, or in giving Tehran access to oil revenues now being held overseas and available only for trade with Iran's five main oil buyers—China, India, Japan, South Korea and Turkey. But could the sanctions take effect fast enough?
We don't know the Islamic Republic's timeline for a bomb. The U.S. needs intelligence sources inside the upper reaches of Iran's nuclear establishment to know how advanced the regime is with building triggering devices—and it is clear, from official discussions of past National Intelligence Estimates, that the Central Intelligence Agency hasn't had such sources.
Through the International Atomic Energy Agency's inspections, the U.S. has measured the regime's advance in producing uranium and plutonium, which is technically the hardest and most expensive part of building weapons, and can calculate accordingly. Given these advances, new sanctions would have to hit like a tidal wave over the next year to bring greater Iranian flexibility and openness to renewed negotiations.
The wiser bet is that sanctions—though important in restoring the U.S.'s negotiating leverage—will fail without other forms of coercion. And Ayatollah Khamenei, if he isn't otherwise deterred, may well respond to new, economy-crushing sanctions by accelerating the nuclear program, presenting Mr. Obama with the choice he most dreads: launch militarily strikes or accept Iran as a nuclear state.
Which brings us to option four: The White House could try to reinforce new sanctions with the credible show of military force to intimidate the Iranian regime. President Hasan Rouhani has rather pleadingly confessed in speeches and in his memoirs that the Anglo-American invasion of Iraq in 2003 scared the clerical regime and led him to advocate, as Tehran's chief nuclear negotiator between 2003-05, a tactical pause in the regime's nuclear aspirations.
To achieve a more lasting impression now would require a significant military operation. Only one target would serve that purpose: Bashar Assad. Syria is Iran's most helpful ally among Arab states. Taking Mr. Assad down would let Tehran know that America's withdrawal from the Middle East and President Obama's dreams of an entente with Iran are over.
Taking out Mr. Assad is unavoidable if Washington is serious about stopping the radicalization of Syria's Sunni population and getting their help in defeating the radical Islamic State, also known as ISIS. And such an about-face by Washington would be shocking—perhaps paralyzing—in Tehran. Yet it is hard to imagine Mr. Obama taking such action.
Which means that Washington and its European allies will most likely angle for another extension of the talks. Ayatollah Khamenei may accept. The Iranian economy, despite the oil-price drop, has been noticeably improving since the interim deal was concluded in January—and the continuation of the talks poses no threat to further nuclear progress.
It is doubtful, though, that things will remain static. Ayatollah Khamenei has no intention of "freezing" Iran's nuclear advance. The weapons program has developed massively on his watch, and in his eyes it is probably essential for the survival of the revolution. Another one of the program's founding fathers, President Rouhani—in whom the Obama administration has put so much hope—almost certainly agrees that retreat is not an option.
For the White House, seeking another extension is probably appealing. The only question, then, is whether Mr. Khamenei will agree to it, and how many more billions in reduced leverage it will cost us. This fearful diplomacy will lead inevitably, as it did with North Korea, to the bomb.
Mr. Gerecht, a former CIA Iranian-targets officer, is a senior fellow at the Foundation for Defense of Democracies. Mr. Dubowitz is the foundation's executive director and heads its Center on Sanctions and Illicit Finance.