Iran has struck a historic deal with the United States and five other world powers (known as the P5+1), agreeing to temporarily halt its nuclear program for six months in exchange for limited and gradual relief of sanctions. Iran agreed to halt its uranium enrichment above 5 percent and the foreign powers agreed to give Iran access to $4.2 billion from oil sales. The six-month period will now give diplomats time to negotiate a more sweeping agreement.

We ask three Stanford scholars to weigh in on the technical and political merits of the agreement. CISAC Senior Fellow, Siegfried Hecker, has been working on Track II diplomacy with Tehran in recent years and was one of a number of Americans who met with Iranian Foreign Minister Javad Zarif and his delegation of diplomats and nuclear scientists after the U.N. General Assembly meeting in New York in September. Iranian-American Abbas Milani is director of Hamid and Christina Moghadam Program in Iranian Studies at Stanford and a contributing editor at The New Republic. Ivanka Barzashka is a CISAC affiliate and a research associate at the Centre for Science and Security Studies, King’s College, London, who specializes in Iran’s nuclear capability.

Just how close did Iran come to being able to build a bomb?

Hecker: Very close, possibly weeks away from making sufficient highly enriched uranium bomb fuel, and six months or so away from building a nuclear weapon. Iran developed the nuclear weapon option under the umbrella of the pursuit of civilian reactor fuel. The technologies for developing reactor fuel and bomb fuel are the same, the difference is in the level of enrichment in Uranium-235: 3 to 5 percent for commercial reactors, as much as 20 percent for research and medical isotope production reactors, compared to roughly 90 percent for weapons. The IAEA reports that Iran has not satisfactorily explained nor given access to work and sites suspected of past nuclear weapons-related activities.

This leads me to conclude that Iran had likely previously done most of the work necessary to build nuclear weapons once it obtained the capacity to produce bomb fuel. Iran’s extensive missile development and testing program also points to Tehran pursuing the option of missile deliverable nuclear weapons.

Does the agreement make it more difficult for Iran to pursue the bomb?

Hecker: Yes, the agreement places temporary limits on the level of enrichment of nuclear material and provides for the conversion or dilution of the highest enriched material (20 percent). It will also temporarily halt Iran installing more or better centrifuges to produce enriched uranium at an increasing rate. Iran has also agreed to temporarily halt construction of the heavy-water reactor in Arak. These steps modestly increase the amount of time it would take Iran to obtain nuclear bomb fuel in a breakout scenario. In addition, increased monitoring of facilities as called for in the agreement will provide us with a better understanding of existing capabilities in known facilities and what may exist in potential covert facilities.

They were very close ... six months or so away from building a nuclear weapon."    - Hecker

Why is Iran’s heavy-water reactor in Arak of such concern?

Hecker: It provides a potential second path to the bomb. Iranian nuclear specialists recently told me in New York that they began to design that reactor 20 years ago to replace the old, small American-provided reactor in Tehran that was being used for medical isotope production and research. Construction is several years behind schedule, but I was told it is close to completion. When complete, it would allow Iran to produce badly needed medical isotopes. But concurrently, the choice of reactor design and power level also means that it will produce enough plutonium to fuel one or two bombs per year if Iran decided to extract the plutonium from the spent reactor fuel. The Iranian specialists told me that they are very keen to find a solution that provides them with the means to make medical isotopes and alleviates international concerns about plutonium production. That’s a worthy goal, but a tall order that was left for the long-term agreement.

What prevented Iran from building the bomb?

Hecker: I believe Iran’s leadership settled for developing the option for the bomb, but has not yet decided to build or demonstrate the bomb. Until recently, it is also likely that Iran did not have sufficient bomb fuel to build the bomb. I believe they now have that capacity; therefore our focus should be on convincing them not to flip the bomb production switch.

Can you envision a long-term agreement that will prevent Iran from building the bomb?

Hecker: Completely getting rid of the bomb option is not possible through military action or sanctions with political pressure. The only chance is through diplomatic means. We need to make it clear to the Iranian regime that they are better off without pursuing the bomb. This will take time. Iran Foreign Minister Zarif told me that even appearing to pursue the bomb is bad for Iran’s nuclear security. Now if we can only get the Iranian leadership to believe that. If Iran wants nuclear energy and relations with the West, I believe we need nuclear integration, not isolation, such as those peaceful programs in South Korea and Japan.

Kerry's video message about the Geneva Talks 

Stepping aside from the leaders and countries involved, what do you think this six-month agreement means to the Iranian people themselves?

Milani: I think in the short run, it has brought them a double sense of joy and relief: joy that war might be averted, and relief that dire days of economic hardships might begin to end and that maybe the country will no longer be a pariah and join the community of nations. But I think there is also some trepidation: Will the interim agreements turn into an enduring policy or will the radicals use the interim sanction relief to get out of the current jam and then resume their policies?

Are you hopeful this is a significant step forward or is it too early to tell?

Milani: I think it is too early to be definitive but my sense is that momentum is building for the successful continuation of the thaw. Policies of the regime in the last years brought the country to the verge of the abyss. One could put a bit of Biblical touch to what President Rouhani himself says: men and women do not live by centrifuges alone. They need bread and freedom.

This is a win for Obama but it also appears to be a huge win for Iranian President Hassan Rouhani. Do you believe he is sincere in his commitment to negotiate and keep the talks on track?

Milani: I think Rouhani is one of the cleverest, most cunning and brutality pragmatic leaders the Islamic Republic has seen. He understands that the status quo is untenable and fashions himself as its potential reforming savior. He needs to make this deal work – one that is acceptable to the West, and the international community and sellable domestically as at least a win-win agreement – if he is to politically accomplish his goals as a disciplined man of great ambitions.

The Israelis are up in arms and Prime Minister Benjamin Netanyahu called the deal “a historic mistake” that gives too much to the Iranians. But shouldn’t they be pleased that Iran has stepped back?

Milani: Many in Israel are up in arms, yet others are confident that the U.S. and EU will pursue their interests while never making a deal that threatens Israel's security. In time I think the second narrative might even dominate Israeli discourse.

Is the deal nothing more than a successful confidence-building exercise?

Barzashka (As told to the Bulletin of the Atomic Scientists on Nov. 25): The agreement, the first in nearly a decade of confrontation over Iran’s nuclear program, is a win for diplomacy and proof that Obama’s strategy of direct engagement with Iran works. Enabled by high-level, face-to-face meetings between Tehran and Washington, the deal was struck despite significant opposition by hardliners in the United States, Iran and Israel.

The P5+1 and Iran adopted tangible, though modest, confidence-building measures that demonstrate both sides are serious about negotiations. The deal reflects reasonable compromises. For example, the P5+1 initially demanded that stockpiled, 20 percent-enriched uranium be shipped out of Iran, but exporting uranium was unacceptable for Tehran. Instead, the two sides agreed that Iran would convert 20-percent enriched uranium hexafluoride to uranium oxide or downblend it to below 5 percent—measures that still buy threat reduction without crossing Iran’s red line.

Finally, the agreement succeeds in building trust by leaving out the hard questions, such as Iran’s right to enrichment, which would be addressed during the next phase of negotiations.

The Obama administration says there is no doubt that Syrian President Bashar al-Assad was responsible for a recent chemical weapons attack near Damascus, which Syrian opposition forces and human rights groups allege killed hundreds of civilians.

Secretary of State John Kerry called the attack a “moral obscenity” and the White House has vowed to respond – though the question of how is still under debate.

The Syrian government denies using nerve agents on its own people and has allowed U.N. weapons inspectors into the country to investigate.

As the U.S. weighs its options and rallies its allies for a possible military strike, Stanford scholars examine the intelligence and discuss the implications of military action against Syria. Those scholars are:

• Martha Crenshaw, one of the nation’s leading experts on terrorist organizations and a senior fellow at the Center for International Security and Cooperation and the Freeman Spogli Institute for International Studies
• Thomas Fingar, former chairman of the National Intelligence Council and currently the Oksenberg-Rohlen distinguished fellow at FSI
• Thomas Henriksen, a senior fellow at the Hoover Institution specializing in U.S. foreign policy and author of the book, “America and the Rogue States”
• Anja Manuel a CISAC affiliate, co-founder and principal at RiceHadleyGates LLC, a strategic consulting firm, and lecturer in Stanford's International Policy Studies
• Allen S. Weiner, a CISAC affiliated faculty member and co-director of the Stanford Program in International Law at the Stanford Law School
• Amy Zegart, an intelligence specialist who is the CISAC co-director and a senior fellow at the Hoover Institution

Does a military strike on Damascus risk further inflaming terrorists operating in Syria who hate the United States?

Crenshaw: I doubt that an American military response to the Assad regime's use of chemical weapons will make al-Qaida and affiliates hate us any more than they already do. The effect on wider public opinion in the Arab and Muslim worlds is what we should be thinking about. As the U.N. noted in a recent report, al-Qaida has a strong presence in Syria and is attracting outside recruits. The Al Nusrah Front in Syria is affiliated with the Iraqi al-Qaida branch. And Hezbollah's involvement has only intensified sectarian violence.

The three-year civil war has claimed some 100,000 lives and forced an estimated 1.9 million Syrians to flee their country, according to the U.N. Why is it taking President Obama so long to take a more assertive policy in Syria?

Manuel: There are no great policy options in Syria. The administration said several times that “stability” in Syria — even if that means a continuing, limited civil war — is more important than a decisive victory over President Bashar al-Assad.  The administration also believes that U.S. military intervention short of using ground troops is unlikely to lead to the creation of a new post-Assad regime that will be friendly to the United States.  Finally, the Obama administration is understandably hesitant to side with the rebel groups, which — in part due to U.S. unwillingness to actively assist moderate Syrian elements for the past two years — have become increasingly radicalized. Al Qaida-allied extremists now make up a growing segment of the rebel movement and some groups are reportedly creating “safe havens” within Syria and Iraq.

Listen to Manuel on public radio KQED Forum about whether U.S. should intervene. 

CISAC's Anja Manuel talks to Al Jazeera America about Syria: 

Have past U.S. intelligence failures made Obama skittish about taking a tougher stance against Syria?

Zegart: Iraq's shadow looms large over Syria. The intelligence community got the crucial WMD estimate wrong before the Iraq war and they absolutely don't want to get it wrong now. People often don't realize just how rare it is to find a smoking gun in intelligence. Information is almost always incomplete, contradictory and murky. Intentions – among governments, rebel groups, individuals – are often not known to the participants themselves and everyone is trying to deceive someone.

What is the intelligence gathering that goes into making the determination that nerve agents were used?

Fingar: The first challenge for the U.S. government is to determine whether and what kind of chemical agents were used. Chain-of-custody issues must be addressed to ensure that samples obtained are what they are claimed to be, and once samples have been obtained, what they are can be established with reasonably high confidence using standard laboratory and pathology techniques.

If it is determined that specific chemical agents were used in a specific place and time, then the next step is to determine who used the agents. Analysts would then search previously collected information to discover what is known about the agents in question, which groups were operating in the area, and whether we might have information germane to the specific incident. Policymakers must be informed about any analytical disagreements if they’re to make informed decisions about what to do in response to the incident.

Pressure on decision-makers to “do something” about Syria may influence their decisions, but it should not influence the judgments of intelligence analysts. If they are suspected of cherry-picking the facts and skewing judgments to fit pre-determined outcomes – they are worse than useless.

See Fingar's comments in The New York Times about the echoes of Iraq.

How do we know the Syrian opposition did not use nerve gas in an effort to provoke military intervention and aid their efforts to topple Assad?

Henriksen: Tracing the precise origin of gas weapons is not an exact forensic science.  It is conceivable that a rebel group staged a "black flag" operation of releasing a deadly gas to provoke a U.S. attack on the Assad regime.  But in this case, both Israeli and Jordanian intelligence reports appear to confirm U.S. identification of Assad as the perpetrator of the chemical attacks. 

If it's confirmed that Syria did use chemical weapons against it own people, is this a violation of the Geneva or Chemical Weapons Conventions?

Weiner:  A chemical weapons attack of the kind that's been described in the media certainly violates the laws of war. Syria, as it happens, is one of only a few countries in the world that is not a party to the Chemical Weapons Convention. Nevertheless, the prohibition on the use of chemical weapons in warfare is a longstanding rule. It is reflected in both the 1907 Hague Convention regulating the conduct of war and the 1925 Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare. (Syria is a party to the 1925 Convention.) The use of a weapon like this also violates the prohibition in the 1977 Geneva Protocols and customary international law on indiscriminate attacks that are incapable of distinguishing between permissible military targets, on the one hand, and the prohibited targeting of civilians and civilian objects, on the other.

If Damascus has violated the conventions, are there non-military actions that can be taken?

Weiner: The illegal use of chemical weapons is a violation of a jus cogens norm, i.e., a duty owed to all states, which means states would have the right to respond to the breach. Such an attack would presumably be a basis for the unilateral imposition of sanctions or severance of relations with Syria. There's an open question under international law whether states not directly injured by Syria's actions could take "countermeasures" that would otherwise be illegal as a way of responding to Syria's illegal action. Under a traditional reading of international law, a violation like this does not give rise to the right by other states to use force against Syria absent an authorization under Chapter VII of the U.N. Charter by the Security Council.

Are there legal means for Washington to bypass the Security Council, knowing that Russia and China would veto any call to action against Syria? 

Weiner: Under the U.N. Charter, a state may use force against another state without Security Council authorization only if it is the victim of an armed attack. Most commentators believe this has been expanded to include the right to use force against an imminent threat of attack. But under the prevailing reading of the U.N. Charter, a mere "threat" to U.S. national security would not provide a justification for the use of force.

But the Obama administration is arguing that Assad's actions pose a direct threat to U.S. national security?

Weiner: Some international lawyers – but not very many – argue that there is a right of humanitarian intervention under international law that would permit states to use force even without Security Council approval to stop widespread atrocities against its own population. But this remains a contested position, and most states, including the United States, have not to date embraced a legal right of humanitarian intervention.

What are some recent precedents in which the U.S. intervened militarily?

Weiner: The situation in Syria is not unlike the one faced in Kosovo in 1999, when a U.S.-led coalition did use force to stop atrocities that the Milosevic regime was committing against Kosovar Albanians. As part of its justification for the use of force, the United States cited the ongoing humanitarian crisis and the growing security threat to the region. What's interesting is that the U.S. was careful to characterize its use of force in Kosovo as "legitimate," rather than "legal."  I am among those observers who think that choice of words was intentional, and that the U.S. during the Kosovo campaign advanced a moral and political justification for a use of force that it recognized was technically unlawful.

How does one know when diplomacy has reached a dead-end and military intervention remains the only course of action?

Henriksen: It has become nearly reflexive in U.S. diplomacy that force is the last resort after painstaking applications of diplomacy. The Obama administration followed that arc dutifully with appeals and hoped that U.N. envoys could persuade Assad to step aside. In retrospect, it seems that U.S. intervention soon after the outbreak of widespread violence in the spring of 2011 would have been a better course of action. Now, Russia, China and Iran have entrenched their support of Damascus. And, importantly, Hezbollah has joined the fight.

Now, with Washington's "red line" crossed by Syria's use of chemical arms, America almost has to strike or lose all credibility in the Middle East and beyond.

Should we be concerned about getting pulled into another long and costly war? Or is there a way to get in, make our point, and get out?

Henriksen: The worry about stepping on a slippery slope into another war in the Middle East is of genuine concern.  Obama's intervention into Libya in early 2011 does provide a model for the use of limited American power. President Bill Clinton's handling of the 77-day air campaign during the Kosovo crisis in early 1999 provides an example of limited interventions. Both these interventions can be analyzed for their pluses and minuses to aid the White House in striking a balance.  But no two conflicts are ever exactly the same.

What is the endgame here?

Henriksen: American interest in the Syrian imbroglio are to check Iran, the most threatening power in the Middle East, and to curtail the conditions lending themselves to spawning further jihadists who will prey on Americans and their allies. At this juncture, it appears that the fragmentation of Syria will become permanent. It's fracturing like that of Yugoslavia in the 1990s and will result in several small states. One or more of these mini-states might possibly align with the United States; others could become Sunni countries with Salafist governments, and the rump state of Assad will stay tight with Iran. The fighting could subside, leaving a cold peace or the tiny countries could continue to destabilize the region. Any efforts that undercut al-Qaida franchises or aspirants are in American interests.