Why It Matters
President Trump's February 2025 directive against Iran to pursue a "snapback of sanctions," an emergency legal move that allows for the fast return of previously lifted international penalties, set in motion events that culminated in European allies invoking the mechanism last summer.
According to a recent CRS In Focus report, that action by the administration fundamentally altered the landscape for nuclear negotiations and the administration's leverage with Tehran.
The Big Picture
The Joint Comprehensive Plan of Action, finalized in July 2015 between Iran and the P5+1 countries, required Iran to constrain its uranium enrichment and heavy water reactor programs and allow International Atomic Energy Agency monitoring. In exchange for compliance, Iran received relief from European Union, United Nations, and U.S. sanctions. The agreement began unraveling after the U.S. withdrawal in May 2018, when the remaining participants, known as the P4+1, made efforts to sustain the deal's benefits for Iran, which Tehran characterized as inadequate. Beginning in July 2019, Iran exceeded JCPOA limits, and in February 2021, it stopped allowing IAEA verification and monitoring related to the agreement and ceased implementing its Additional Protocol.
Events accelerated in 2025. U.S.-Israeli airstrikes on Iranian nuclear facilities occurred in June 2025, including facilities associated with Iran's enrichment program. The IAEA withdrew inspectors from Iran following the June 2025 airstrikes, and has been unable to inspect the attacked facilities. France, Germany, and the United Kingdom invoked the snapback mechanism on August 28, 2025, resulting in UN sanctions reimposition on September 27, 2025, just before the October 18 deadline after which the snapback mechanism would have permanently expired. Secretary of State Marco Rubio praised the European action as an act of decisive global leadership.
China, Iran, and Russia contested the E3's standing to invoke snapback in an October 18, 2025 letter to the Security Council, arguing that the E3 had themselves failed to fulfill their JCPOA commitments.
The Bottom Line
Iran currently remains bound by its NPT obligations, but not by JCPOA transparency measures or physical constraints on its enrichment program. The IAEA now only monitors Iran under Tehran's comprehensive safeguards agreement of indefinite duration.
A June 2026 memorandum of understanding between the parties is silent on the future of IAEA safeguards in Iran, leaving unresolved whether inspectors will regain access to previously struck facilities or what verification regime, if any, will govern Tehran's nuclear activities going forward.
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