March 29, 2023

Disarming the Bomb

Distilling the Drivers and Disincentives for Iran's Nuclear Program

Executive Summary

Negotiations to return to the Joint Comprehensive Plan of Action (JCPOA), known commonly as the Iran nuclear deal, reached an impasse this past year. Further, Iran made parallel decisions to brutally crack down on a nationwide protest movement and to inject itself into the conflict in Ukraine by furnishing Russia with weapons. These decisions may have rendered the impasse insurmountable. U.S. President Joe Biden has not retreated from the U.S. policy that it will never allow Iran to obtain a nuclear weapon. However, Iran’s maximalist demands at the negotiating table, along with its domestic and foreign activities, have made it politically impossible for the United States and Europe to pursue further negotiation. Further complicating the situation and perhaps rendering the JCPOA increasingly obsolete, critical provisions of the original deal will expire in 2025 and 2030. The United States and the international community must consider how to constrain Iran’s pursuit of a nuclear deterrent in a post-JCPOA world, in which Iran has never been closer to achieving a bomb.

The CNAS Middle East Security Program designed and ran a scenario exercise in October 2022 to identify key factors that might accelerate or decelerate Iran’s nuclear program in 2024. Additionally, the exercise explored how Iran, the United States, Israel, and the Gulf nations could prioritize their own national security objectives with respect to Iran’s nuclear program, along with the potential actions each might take to accomplish those objectives.

The exercise examined two scenarios. Scenario 1 explored key countries’ policy actions and perspectives if the United States and Iran failed to reenter the JCPOA. Scenario 2 explored key countries’ policy actions and perspectives if the United States and Iran successfully renegotiated a return to compliance with the JCPOA and faced the imminent expiration of elements of the deal.

Overall observations from the exercise suggest that Iran’s leadership’s primary concern is self-preservation. Pursuing a nuclear program is secondary and ultimately serves to advance the primary objective (self-preservation). U.S. policymakers face many challenges in rallying partners against Iran while prioritizing a negotiated approach to curtail Iran’s nuclear program.

The United States and the international community must consider how to constrain Iran’s pursuit of a nuclear deterrent in a post-JCPOA world, in which Iran has never been closer to achieving a bomb.

Additionally, Gulf states attempting to coexist near a dangerous and mercurial neighbor are in a precarious position. Instead of limiting or halting Iran’s nuclear program directly, policymakers could use existing tools to convince Iran’s leaders that pursuing nuclear capability endangers the regime, which contradicts the nuclear program’s purpose. Potential tools include public and private messaging, as well as preparing military action that targets the regime and is predicated on continued nuclear advancement.

Moreover, the exercise highlighted how Iran’s malicious activities impede the policy decision-making of its neighbors. The United States should develop an integrated security architecture in the region to establish greater defensive military capability and interoperability among its partners, thus reducing their susceptibility to coercion through Iranian military action. This report analyzes the key themes and insights from the scenario exercise and offers policy recommendations to prevent Iran from pursuing a nuclear weapon.


On July 14, 2015, Iran, the European Union (EU), and the U.N. Security Council’s five permanent members, China, France, Russia, the United Kingdom, and the United States, plus Germany—known as the P5+1—signed the Joint Comprehensive Plan of Action (JCPOA) to restrict Iran’s nuclear program in exchange for relieving many U.N., U.S., and EU economic sanctions on the regime. The nuclear deal imposed binding limitations on Iran’s uranium enrichment program for 10 to 15 years and expanded international verification and monitoring of Iran’s nuclear fuel cycle. In addition, U.N. Security Council Resolution (UNSCR) 2231 endorsed the nuclear deal and provided the Security Council with the authority to monitor the deal’s implementation. See Appendix B for the major JCPOA provisions, areas covered, and critical sanctions timeframes.

All parties remained in compliance with the JCPOA until May 8, 2018, when then-President Donald Trump officially withdrew the United States from the agreement. The Trump administration argued the deal was deeply flawed from the start, citing Iran’s continued support to regional proxies and terrorist organizations and weapons development. Essentially, while Iran may have been in technical compliance with the JCPOA, it was not in compliance with the spirit of the deal. Unilaterally, the United States restored sanctions previously removed under the JCPOA and began implementing sanctions under a new policy—the maximum pressure campaign. The campaign sought to force Iran to negotiate a more comprehensive deal by imposing far-reaching sanctions. Sanctions implemented under the maximum pressure campaign would limit Iran’s ability to purchase U.S. dollars and to trade in gold, aluminum, steel, and other key resources. Additionally, the campaign sought to drive Iran’s oil exports down from 1.5 million barrels a day to zero.

Although the United States withdrew from the deal, the other signatories remained within the agreement framework. In January 2019, Britain, Germany, and France established the Instrument in Support of Trade Exchanges (INSTEX) to enable European nations to continue humanitarian trade with Iran amid U.S. sanctions and following Iran’s suspension from SWIFT (Society for Worldwide Interbank Financial Telecommunication), a Belgium-based international financial messaging service. Along with establishing INSTEX, European signatories publicly supported the continuation of the JCPOA.

Over the next two years, Iran continued advancing nuclear activities, exceeding proscribed limitations on enriching and stockpiling uranium, resuming operations at the Arak facility, and installing advanced centrifuges.

Following the U.S. withdrawal, Iran remained compliant with the JCPOA for about a year. However, as the United States ramped up sanctions, the Iranian regime deliberately and incrementally fell out of compliance with its JCPOA commitments. Over the next two years, Iran continued advancing nuclear activities, exceeding proscribed limitations on enriching and stockpiling uranium, resuming operations at the Arak facility, and installing advanced centrifuges.

Tensions between the United States and Iran continued to escalate. In multiple incidents in 2019, Iran attacked and seized oil tankers docked in the Gulf of Oman and transiting the Strait of Hormuz. In September 2019, Iran attacked and damaged Saudi Aramco oil infrastructure in Abqaiq and Khurais, two oil facilities located in Saudi Arabia, using uncrewed aerial vehicles (UAVs), loitering munitions, and cruise missiles, though Iran denied orchestrating the attack. U.S.-Iran tensions rose from December 31, 2019, to January 1, 2020, when militias in Iraq with close ties to Iran staged a violent protest at the gate of the U.S. embassy in Baghdad against a recent U.S. strike on an Iran-backed militia compound. On January 3, 2020, the U.S. military launched a Hellfire missile at a vehicle and killed the intended target, Islamic Revolutionary Guard Corps-Quds Force (IRGC-QF) Commander Qasem Soleimani, with President Trump stating that Soleimani was planning large-scale attacks on U.S. embassies. Iran retaliated on January 8, 2020, by firing ballistic missiles at the Ain al-Assad and Irbil bases in Iraq, which hosted hundreds of U.S. troops.

Amid this escalation and during the 2020 U.S. presidential campaign, then-candidate Joe Biden expressed his intention that if elected, he would seek to return the United States into compliance with the nuclear deal if Iran also became compliant with the agreement’s terms. Despite these overtures, Iran continued expanding nuclear enrichment activities. On December 2, 2020, Iran’s parliament and Guardian Council passed legislation to increase enrichment levels up to 20 percent and announced that it would suspend the Additional Protocol if sanctions were not lifted after 60 days. Two days later, the International Atomic Energy Agency (IAEA) released a report that the Natanz enrichment facility would add three additional IR-2m cascades. Then–Iranian President Hassan Rouhani stated that restoring the 2015 nuclear deal was possible without negotiations, claiming that Iran’s recent actions did not violate the JCPOA.

Following Biden’s election victory, his administration chose to pivot its approach and immediately opened the door for negotiations with Iran. In January 2021, newly appointed National Security Advisor Jake Sullivan announced that the United States would begin negotiations on Iran’s ballistic missile program after both parties returned to compliance with the deal. This negotiation would require the cessation of U.S. sanctions related to Iran’s nuclear program and a demonstrated decrease in uranium enrichment levels and enrichment-related activities by Iran. Weeks later, the IAEA released a report that Iran planned to begin researching uranium metal production to fuel the Tehran Research Reactor (TRR). The TRR is Iran’s light water research reactor that is under the Tehran Nuclear Research Center. Since its creation, the TRR produced medical isotopes and highly enriched uranium (HEU) fuel. This was a direct violation of the JCPOA, which prohibits the production and acquisition of uranium metal for 15 years. In early February 2021, Sullivan announced that the administration was “actively engaged with the European Union” with the goal of restoring the JCPOA. That same month, the National Security Council principals committee convened to discuss Iran, with a particular focus on the United States pursuing a swift return to the deal before Iran’s June presidential elections.

On April 15, 2021, representatives from Iran and the EU convened in Vienna to discuss a possible plan to revive the JCPOA. (EU Delegation in Vienna via Getty Images)

EU Delegation/Getty Images

Iranian leadership continued to approve increased levels of enrichment. On February 22, 2021, Iranian Supreme Leader Ayatollah Ali Khamenei stated that Iran may enrich uranium up to 60 percent purity despite U.S. pressure on the Iranian nuclear program to decrease enrichment levels. The following day, Iranian Foreign Minister Javad Zarif announced via Twitter that Iran would suspend the implementation of the Additional Protocol. Two months later, the Joint Commission on the JCPOA—under EU guidance and comprised of China, France, Germany, Russia, the United Kingdom, and Iran—met for its first session in Vienna to facilitate a return to the JCPOA. No deal was reached after five additional rounds of negotiations in June 2021. That same month and immediately after taking office, then–Israeli Prime Minister Naftali Bennett criticized newly elected Iranian President Ebrahim Raisi for Iran’s increased nuclear activity and urged the United States to abandon negotiations. For five months, Iran took a hiatus in returning to talks until November 2021 when it met again with the P5+1 and the EU in Vienna.

In February 2022, 33 Republican senators wrote a letter to President Biden urging him to seek congressional approval to revive the JCPOA. This came days after the Biden administration issued waivers allowing Russian, Chinese, and European companies to work with Iran’s nuclear program to pursue nonproliferation efforts to make weapons development more challenging at Iranian nuclear sites. Despite Russia’s invasion of Ukraine during the same month, State Department Spokesperson Ned Price reiterated that the United States and Russia would continue to cooperate on nuclear negotiations. For the most part, Russia’s invasion of Ukraine did not disrupt these talks. However, the Russia-Ukraine conflict would impose on nuclear negotiations months later when reports surfaced that Iran was supplying weapons and training to aid Russia in the conflict.

In May 2022, U.S. Special Envoy for Iran Robert Malley testified before the Senate Foreign Relations Committee that Iran could potentially develop a nuclear weapon without a restored JCPOA. Additionally, a return to the agreement could increase Iran’s nuclear breakout time from a few weeks to one year under the constraints of the deal. Two IAEA reports followed, indicating that Iran had not explained the presence of uranium at three undeclared sites and that it possessed 43 kilograms of uranium enriched to 60 percent and 238 kilograms of uranium enriched to 20 percent. Mohammad Eslami, head of the Atomic Energy Organization of Iran, vehemently rejected the IAEA’s findings and resisted efforts by the IAEA to further investigate the existence of uranium at undeclared nuclear sites.

Beyond Iran’s diplomatic intransigence, other events involving Iran began to obscure nuclear negotiations, making dialogue both impolitic and potentially self-defeating.

In September 2022, two IAEA reports explained that Iran had not complied with the IAEA’s safeguards investigation since the prior quarterly report and that its stockpile of enriched uranium continued to grow. Following demands from Iran’s negotiators that any return to the JCPOA must include the termination of any ongoing IAEA investigations (which were triggered by Iran’s participation in the Non-Nuclear Proliferation Treaty, not by the JCPOA), U.S. Secretary of State Antony Blinken stated any near-term agreement with Iran now seemed unlikely. That same month, David Barnea, director of the Mossad, Israel’s foreign intelligence agency, noted that a restored JCPOA would not give Iran immunity from Mossad operations, including on Iranian soil. However, this threat had little effect as Iran continued to enrich uranium, reaching 60 percent purity at its Fordow plant in November 2022.

Beyond Iran’s diplomatic intransigence, other events involving Iran began to obscure nuclear negotiations, making dialogue both impolitic and potentially self-defeating. In mid-September 2022, young Iranians across the country began protesting the death of Mahsa (Jina) Amini, a 22-year-old Kurdish-Iranian woman, beaten to death by Iran’s morality police after being detained for improperly wearing her headscarf. In Ukraine, Russia began using Iranian-manufactured loitering munitions—the Mohajer-6, Shahed-131, and Shahed-136—to target critical infrastructure in Ukraine, including its power plants. While the United States was aware of these transfers from Iran, there were no public accounts of these weapons being used in the Russia-Ukraine conflict until this time. According to reports, Moscow and Tehran reached an agreement to construct drones on Russian soil to increase Russia’s stockpile of killer drones. European countries and the United States have claimed that the increased production of these drones violates UNSCR 2231, the same provision that endorsed the JCPOA. In light of Iran’s continued UAV proliferation to Russia and brutal crackdown on domestic protests, the United States has tabled negotiations for a revived nuclear deal. However, the United States has not ruled out the prospect of engaging in diplomacy with Iran in the future.

Whether or not the United States and Iran can agree to return to compliance with the JCPOA, critical provisions of the nuclear deal will sunset in the coming years. The deal prescribes that in October 2023, also known as Transition Day, the U.N. will lift missile restrictions, the EU will lift its remaining nuclear sanctions, and the United States will lift sanctions from certain entities. On October 2025, also known as Termination Day, UNSCR 2231 would expire, ending the sanctions “snapback” mechanism that enables parties to declare the other out of compliance with the deal.

*Cover image credits: Iranian Presidency Office Handout/EPA, Shawn Thew/Pool/REUTERS, Mohammed Zaatari/AP file, Hossein Velayati/Wikimedia Commons

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