Iran responded to the United States' withdrawal from the Joint Comprehensive Plan of Action (JCPOA) in May 2018 by breaching the limits on its nuclear program that were put in place by the accord and investing in new nuclear capabilities. As a result, Iran’s advances have brought the country to the threshold of nuclear weapons. Furthermore, Iran reduced IAEA monitoring activities in 2021, making it more challenging for the agency to provide assurance that Iran’s nuclear program is peaceful and to account for all nuclear materials within Iran.
Expanded Uranium Enrichment
Under the JCPOA, Iran’s uranium enrichment program was subject to verifiable limitations. These limits included:
- Enriching uranium to no more than 3.67 percent, a level suitable for nuclear power reactors, until 2031.
- Stockpiling no more than 202 kilograms of uranium enriched to 3.67 percent until 2031.
- Enriching uranium using only 30 cascades of IR-1 centrifuges (5,060 machines) at Natanz until 2026.
As a result of these restrictions, the time it would take Iran to produce enough weapons-grade uranium for one bomb (25 kilograms of uranium enriched to 90 percent), was about 12 months for the first decade of the agreement.
Iran began breaching limits imposed by the nuclear deal in 2019, one year after the United States withdrew from the accord. Since then, it has expanded its uranium enrichment program. Iran’s advances included enriching uranium to 60 percent, a level close to weapons-grade that has no practical civilian application, and deploying advanced centrifuges that enrich uranium more efficiently. Iran has gained knowledge from these activities that cannot be fully reversed.
As of November 2024, Iran’s stockpile of enriched uranium included:
- 182 kilograms of uranium enriched to 60 percent.
- 840 kilograms of uranium enriched to 20 percent.
- 2,595 kilograms of uranium enriched to 5 percent.
Iran also significantly expanded its uranium enrichment capacity. As of November 2024, Iran had installed at its Natanz and Fordow uranium enrichment facilities:
- 42 cascades of operating IR-1 centrifuges.
- 37 cascades of IR-2 centrifuges, of which 15 are operating.
- 13 cascades of operating IR-4 centrifuges.
- 15 cascades of IR-6 centrifuges, of which 7 are operating.
Iran’s expanded uranium enrichment capacity and larger stockpiles of 20 and 60 percent enriched uranium have significantly reduced Iran’s breakout, or the time it takes to produce enough weapons-grade material for a bomb. As of late 2024, Iran can produce enough weapons-grade uranium for 5-6 bombs in less than two weeks.
Iran announced additional plans in late-2024 to further expand its uranium enrichment program. These activities will further decrease Iran’s breakout to multiple bombs worth of weapons-grade uranium. Specifically, Iran notified the IAEA that:
- It plans to install an additional 32 cascades of centrifuges.
- It will increase the production of uranium enriched to 60 percent by feeding 20 percent enriched uranium into two cascades of IR-6 centrifuges.
The IAEA estimated that Iran’s monthly production of 60 percent material at Fordow will jump from 4.7 kilograms per month to 37 kilograms per month as a result of increasing the feed from 5 percent to 20 percent. Conducting this activity at Fordow, a deeply buried nuclear facility, further increases proliferation risk because Fordow is more challenging to destroy with conventional military strikes. Iran was prohibited from enriching uranium at that location for 15 years under the JCPOA.
Plutonium Pathways
Iran is continuing to develop the unfinished Arak reactor based on the modifications agreed to in the JCPOA. It is unclear when the reactor will be operational. However, the revised reactor design, which reduces the plutonium produced by the reactor, combined with ongoing IAEA monitoring of the site, effectively blocks the plutonium pathway for nuclear weapons.
Reduced Monitoring
Iran continues to implement its comprehensive safeguards agreement (CSA), as legally required by the nuclear Nonproliferation Treaty (NPT). The CSA gives the IAEA regular access to sites in Iran that house nuclear materials, such as reactors, uranium enrichment facilities, and fuel fabrication sites. However, in February 2021, Iran halted more intrusive verification measures required by the JCPOA, such as:
- Implementation of the additional protocol, a more intrusive safeguards agreement that expanded IAEA access to information and sites.
- Daily access to Natanz and Fordow.
- Continuous surveillance of certain sites.
- Implementation of Modified Code 3.1 to its safeguards agreement, which requires Iran to provide design information about new facilities to the agency as soon as the decision is made to begin construction.
The IAEA argues Iran cannot unilaterally suspend Modified Code 3.1 and the IAEA’s Board of Governors has censured Iran for failing to implement this part of its safeguards agreement.
Iran’s decision to suspend these monitoring provisions has an impact on proliferation risk and the IAEA’s ability to verify if Iran’s nuclear program remains peaceful. As a result:
- There is an increased risk that Iran could attempt to breakout between IAEA inspections.
- The IAEA can no longer access certain facilities that support Iran’s nuclear program.
- The IAEA cannot provide assurance that materials critical to Iran’s nuclear program, such as centrifuges and uranium ore concentrate, are accounted for and have not been diverted to a covert program.
- The agency cannot conduct short-notice inspections allowed under the additional protocol.
- The IAEA does not have access to early design information for new nuclear facilities, which the agency uses to develop an effective safeguards approach.
Weaponization
Iran pursued an organized nuclear weapons development program in violation of its NPT commitments. The program ended in 2003, according to IAEA and U.S. intelligence assessments.
The U.S. Intelligence Community continues to assess that Iran is not building a nuclear weapon, but warned in November 2024, that Iran’s nuclear activities “better position it to produce” nuclear weapons, “if it so chooses.” That report also highlighted Iran continues to “publicly discuss the utility of nuclear weapons.”
In October 2024, Central Intelligence Agency Director William Burns said he is “reasonably confident” that the United States, working with “friends and allies” would be able to detect weaponization work “relatively early on.”
The public debate in Iran over the value of a nuclear deterrent intensified in 2024, when senior Iranian officials suggested that Iran may rethink Supreme Leader Ayatollah Ali Khamenei’s fatwa prohibiting nuclear weapons if security conditions warranted it. For example, in November 2024, Kamal Kharrazi, an advisor to the Supreme Leader, said that Iran will “modify its nuclear doctrine” if “an existential threat arises.”
Iranian officials, including the current and former heads of the Atomic Energy Organization of Iran, also have noted that Iran possesses the necessary technical capabilities to weaponize.