Iran has been a critical player in the Syrian war since 2011, crafting a complex foreign policy and military strategy to preserve its Syrian ally. What have been the drivers of Iranian decision-making in this conflict? And how has Iranian strategy evolved over the course of the war? This article argues that the logic of deterrence has been fundamental not just for shaping the contours of Iran–Syria relations since the Islamic Revolution of 1979, but also for determining the overall trajectory of Iranian strategy in the Syrian war. The authors outline Iran's decision-making calculus and divide the country's strategy on Syria after the Arab Spring into four primary phases: 1) a ‘Basij’ strategy to establish local militias in Syria; 2) a regionalization strategy to incorporate transnational fighters and militias in the war effort; 3) an internationalization strategy to incorporate Russia and balance the United States; and 4) a post-ISIS deterrence strategy to balance against the United States, Turkey and Israel. Iran's Syria strategy progressively escalated in response to the possible defeat of its ally and the deterioration of its forward deterrence capacities against the United States and Israel. Today, the potential for direct inter-state conflict is rising as proxy warfare declines and Iran attempts to maintain the credibility of its forward deterrence.

Although there are a number of major disagreements between Iran, Russia and Turkey, what is important in the end is that they are all opposing the current US policies in Syria. All three countries have suffered from US sanctions and all have serious trust issues with the Trump administration. Emphasising this common ground, Iran's Supreme Leader Ayatollah Ali Khamenei told Russian President Vladimir Putin earlier in September that "the US is containable" and that Iran and Russia should continue close cooperation towards this goal. Whichever strategy Iran chooses to pursue, the US will likely feel the pressure on the ground soon enough. That could end up being an effective deterrent against US plans of opening additional fronts against Iran in the Middle East.

Trump's strategy appears to be one of brinkmanship—rocking the boat in hopes that the other party is less risk-tolerant and will give in before the boat capsizes.

The dramatic seizure of American navy sailors in the Persian Gulf by the Iranian Revolutionary Guards could have endangeredImplementation Day—when on January 16 Iranian compliance with the nuclear agreement so far was verified and the international sanctions against Iran lifted. Instead of derailing the deal, however, the Guards used the incident, as well as the highly publicized prisoner swap, as symbolic events to send the world a message.By detaining the vessels and broadcasting images of its crew to a global audience, the Guards used the opportunity to reveal the future path of Iranian foreign policy in the wake of the nuclear agreement—a path that can be best described as ‘pragmatic revolutionism.’

An audio recording of a public talk by Brian Katulis, Senior Fellow, Center for American Progress, Washington, DC.

"Now that President Barack Obama has secured more than enough votes in the U.S. Senate to assure the implementation of the agreement with Iran on nuclear issues and sanctions, we can focus on the lessons learned from the process’ intense political dynamics. Three in particular stand out: U.S.-Israeli, U.S.-Saudi Arabian/Gulf Cooperation Council (GCC), and GCC-Iranian relations. U.S.-Israeli bilateral ties get the most attention these days, but all three are equally important, and turbulent in their own ways."

The July 14, 2015 comprehensive nuclear deal between Iran and the P5+1 (known as the Joint Comprehensive Plan of Action or JCPOA) consists of the agreement itself and five technical annexes: Annex I – Nuclear-related measures; Annex 2 – Sanctions-related commitments; Annex III- Civil Nuclear Cooperation; Annex IV – Joint Commission; and Annex V – Implementation Plan. The version issued by the EU is used here because pages and paragraphs are numbered in proper order.

This article describes the main elements of the JCPOA. In coming days, the Belfer Center plans to publish a more detailed description and assessment of the agreement.

Graham Allison, Director of the Belfer Center for Science and International Affairs, testified before the Senate Foreign Relations Committee on lessons from prior weapons of mass destruction negotiations for the current talks with Iran over its nuclear program. Drawing on arms control agreements during the Cold War and the post-Cold War era, he argued that negotiated agreements on nuclear weapons are a crucial part of American national security although they are complementary to, and not an alternative to, other military, diplomatic, covert, and economic means of geopolitical competition, that no arms agreement is perfect from the perspective of both sides as they are by nature negotiated settlements, claims that the United States can't or should make agreements with "evil" regimes or those that cannot be trusted are false, the United States can make agreements with regimes that it is trying to contain or subvert in other ways, and which are in turn engaging in other actions that are threatening American citizens and soldiers, arms control agreements overall have reduced the number of nuclear weapons and helped reduce the likelihood of war, and that there is no "good" or "bad" agreement on its own, but only when assessed against alternative options.

William Tobey, Senior Fellow at the Belfer Center for Science and International Affairs, testified before the Senate Foreign Relations Committee on lessons from prior arms control and disarmament agreements for the current negotiations with Iran. Using examples from Iraq, North and Libya, he identified five key patterns for arms control negotiators to be cognizant of, including the fact that decisions to disarm are usually incomplete and taken incrementally, deceptive actions by the proliferator can appear as progress, strong verification and intelligence measures can deter cheating while lax verification can encourage it, verification is built on checking declarations for inconsistencies, and inspections are only as effective as political support.  From these lessons, he identified three key lessons, including a complete declaration of nuclear activities is crucial, unwillingness to provide this declaration is evidence of Iran's willingness to comply with a full agreement, and successful agreements require vigilance over time, and cannot be considered solved after an agreement is signed.

To assist Members of Congress and observers in analyzing these issues and judging a potential comprehensive agreement, the Belfer Center prepared this brief to outline the key facets of sanctions against Iran. Written as an addendum to our April policy brief, ‘Decoding the Iran Nuclear Deal,’ this report is driven by the policy debate’s leading questions.