Introduction
The Joint Comprehensive Plan of Action (JCPOA), concluded on July 14, 2015, in Vienna, established a diplomatic framework to ensure the peaceful nature of Iran’s nuclear program. Its Preamble explicitly binds parties, including the E3 (France, Germany, and the United Kingdom), to act in accordance with the purposes and principles of the United Nations Charter, stating: “The E3/EU+3 and Iran reaffirm their commitment to the purposes and principles of the United Nations as set out in the UN Charter.” This obligates all participants—including the E3—to act in good faith and abide by Article 2(4)’s prohibition on the threat or use of force. The JCPOA’s Dispute Resolution Mechanism (DRM), notably the snapback provision under UN Security Council Resolution 2231, allows for the reimposition of UN sanctions if Iran violates its nuclear commitments. This article evaluates whether the E3’s conduct in response to the June 2025 military strikes compromises their legal authority to invoke the snapback mechanism, analyzing their actions under international law doctrines and the impact of these strikes on the JCPOA framework.
The analysis incorporates principles such as good faith (Vienna Convention on the Law of Treaties, Article 26), abus de droit (prohibition of abusive exercise of rights), estoppel, and UN Charter obligations, with a focus on Article 2(4). It also examines whether the military strikes constitute a fundamental change of circumstances under Article 62 of the Vienna Convention, rendering prior UNSC resolutions obsolete, and concludes with a reasoned opinion on the JCPOA’s current status and the E3’s enforcement capacity.
Background and context
The JCPOA, formalized between Iran and the P5+1 (China, France, Russia, UK, US, and Germany) along with the European Union, aims to limit Iran’s nuclear activities in exchange for effective sanctions-lifting. Endorsed by UN Security Council Resolution 2231 (2015), the agreement includes a DRM that encourages parties to resolve disputes diplomatically before resorting to snapback, which allows any JCPOA participant to trigger the reimposition of UN sanctions within 30 days unless the Security Council passes a resolution to continue sanctions-lifting. A permanent Security Council member can veto such a resolution, making snapback difficult to halt.
The E3, as active JCPOA participants, are bound by the agreement’s obligations, including acting in good faith, supporting the agreement’s goals of nuclear non-proliferation and regional stability, and adhering to international law, notably UN Charter Article 2(4). The snapback mechanism’s legitimacy depends on the invoking party’s compliance with these principles.
Facts of the June 2025 military strikes
On June 13, Israel launched a surprise attack on dozens of Iranian nuclear and military sites, citing alleged proximity to nuclear weapons capability. Iran firmly rejected these allegations, reiterating that its nuclear program remains peaceful. Iran responded in self-defence (acting under Article 51 of the UN Charter) with retaliatory missile strikes, escalating into a short air war. On June 22, the United States, despite having withdrawn from the JCPOA in 2018, carried out airstrikes on Fordow, Natanz, and Isfahan using 30,000-pound bunker-buster bombs and cruise missiles. These facilities are central to the IAEA’s verification regime under the JCPOA, and their destruction severely undermined the agreement’s monitoring infrastructure.
A ceasefire was brokered on June 23. However, the E3’s response was notably restrained. UK Prime Minister Keir Starmer referred to the strikes as “action to alleviate” a perceived threat. Germany’s Chancellor Friedrich Merz described Israel’s attacks as “dirty work” on behalf of the international community. EU foreign-policy chief Kaja Kallas issued a vague call to “step back” (EU Statement, June 14, 2025). In a subsequent reaction, Kallas posted on social media that “negotiations on ending Iran’s nuclear programme should restart as soon as possible”. A joint E3 statement on June 16 deplored the escalation but avoided attributing responsibility. On June 22, their communiqué praised U.S. strikes as necessary to “prevent Iran from acquiring a nuclear weapon,” with France’s president asserting the “legitimacy in neutralizing Iran’s nuclear structures.” When Iran’s Atomic Energy Organization requested an IAEA investigation, the E3 refused to support the call, casting doubt on their commitment to the JCPOA’s dispute resolution framework.
Analysis of the E3’s conduct
1) Good faith (Vienna Convention, Article 26) and the Clean Hands Doctrine
The obligation to perform treaties in good faith (pacta sunt servanda) is enshrined in Article 26 of the Vienna Convention on the Law of Treaties. The JCPOA’s object and purpose—maintaining a peaceful nuclear program through monitoring—were gravely undermined by the destruction of Fordow, Natanz, and Isfahan. The E3’s failure to condemn these violations, coupled with their subsequent praise of the U.S. strikes, signals a clear breach of this duty. Their silence and endorsement undermine the agreement’s operational framework and violate the principle of good faith (see VCLT Article 26; JCPOA Preamble; IAEA Implementation Reports).
Furthermore, the equitable principle that “he who comes into equity must come with clean hands” (recognized in ICJ jurisprudence, e.g., Nicaragua v. United States, Merits, 1986, para. 282) applies to the invocation of treaty remedies like snapback. By tacitly endorsing or failing to oppose the unlawful use of force that destroyed the very subject matter of the agreement they seek to enforce, the E3 have arguably soiled their hands. This complicity, evidenced by their statements praising the U.S. strikes as “necessary” and “legitimate,” potentially bars them from seeking the equitable remedy of snapback under the JCPOA’s DRM. Their actions could be seen as “approval” under Article 16 of the ILC Articles on State Responsibility, further implicating them in the underlying illegality.
2) Estoppel (Bolstered with Specific Precedent)
The legal doctrine of estoppel, recognized by the ICJ in Temple of Preah Vihear (Cambodia v. Thailand, 1962), bars a party from acting inconsistently with previous commitments upon which another party has reasonably relied. In a definitive demonstration of their legal position, the E3 jointly stated to the UN Security Council on August 20, 2020: “the U.S. cannot be considered a JCPOA participant… and thus cannot initiate the snapback mechanism” (E3 Letter to UNSC President, S/2020/822). This unambiguous position established a clear expectation for all JCPOA participants, including Iran, regarding the prerequisites for invoking snapback.
Their current conduct represents a radical and legally untenable reversal. Not only have they failed to act in defense of the JCPOA against attacks by the very non-participant (the U.S.) they previously deemed ineligible for snapback, but they have actively praised that non-participant’s destruction of core JCPOA infrastructure. This inconsistency – vehemently denying snapback rights to a withdrawn party in 2020, while now effectively supporting that party’s destruction of the agreement’s foundation in 2025 – fundamentally undermines their credibility. Iran reasonably relied on the E3’s 2020 position regarding participant status and good standing. The E3 are now estopped from invoking the snapback mechanism themselves, having failed to uphold the agreement’s integrity and actively aligned with forces that demolished its physical basis. Their silence in the face of Iran’s request for an IAEA investigation further compounds this inconsistency, mirroring the acquiescence found to create estoppel in Preah Vihear.
3) UN Charter, Article 2(4) & Jus Cogens
Article 2(4) of the UN Charter prohibits the use of force against the territorial integrity or political independence of any state. The U.S. and Israeli attacks were textbook violations of this provision, which has attained the status of a peremptory norm of international law (jus cogens) as affirmed by the ICJ in Nicaragua v. United States (Merits, 1986, para. 190). Although the E3 did not participate directly, their silence, political alignment with the attackers, and subsequent praise of the U.S. strikes amount to acquiescence and endorsement. Such acquiescence in the face of a blatant violation of a jus cogens norm is itself a serious breach of international law, particularly given their explicit obligations under the JCPOA Preamble and Section 36 to uphold the UN Charter and safeguard the agreement. Their conduct is incompatible with their role as guardians of a treaty grounded in peaceful dispute resolution and non-proliferation.
4) Breach of JCPOA commitments
The JCPOA’s Section 36 requires parties to address disputes through consultation and refrain from measures that jeopardize the agreement. The E3’s refusal to support Iran’s request for an IAEA investigation—and their failure to even acknowledge that JCPOA-mandated sites were targeted—constitutes a clear breach of this commitment. Even if the E3 argue their statements were merely neutral or reflected security concerns, Section 36 imposes an active duty to “resolve any issue arising with respect to the implementation of this agreement.” Their categorical refusal to support an investigation into the destruction of the agreement’s core verification infrastructure is a direct violation of this duty. Furthermore, their praise for the U.S. strikes goes far beyond neutrality, actively endorsing measures that annihilated the JCPOA’s foundation. Their reliance on unverified allegations of an “imminent threat” to justify their stance, while simultaneously blocking the established verification mechanism (IAEA investigation), starkly contradicts their JCPOA obligations and highlights bad faith.
Legal Ramifications on the Snapback Mechanism and UNSC Resolutions
1) Loss of standing to invoke Snapback
The legal authority to invoke snapback presumes the invoking party is in good standing. Under Article 60 of the Vienna Convention, a material breach of treaty obligations by one party may discharge the other from its commitments. The E3’s demonstrated breach of their JCPOA obligations through inaction, tacit endorsement of aggression, active praise of a non-participant’s destructive actions, violation of good faith, and breach of Section 36 fundamentally compromises their standing to invoke the DRM or snapback (VCLT Article 60; JCPOA Section 37). Their “clean hands” are essential for invoking an equitable remedy like snapback; their complicity in the agreement’s destruction forfeits this standing.
2) Fundamental change of circumstances (VCLT, Article 62) & supervening impossibility (VCLT, Article 61)
Article 62 permits suspension or termination of a treaty if an unforeseen change radically alters the nature of obligations. Article 61 applies if an object indispensable for execution disappears or is destroyed. The U.S.-Israeli destruction of critical nuclear infrastructure central to the JCPOA’s verification regime constitutes both a fundamental change and supervening impossibility. With the monitoring architecture physically obliterated, the very foundation of reciprocal obligations has vanished. As the ICJ stated in Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (1997, para. 104), a fundamental change must have “radically transformed the extent of obligations still to be performed.” The complete destruction of the facilities that were the primary subject of monitoring and restraint under the JCPOA meets this high threshold. Iran may reasonably argue that the original balance of obligations has been erased, releasing it from further performance. Reimposing sanctions designed to constrain activities rendered impossible by external force is legally incoherent.
3) Obsolescence and collapse of the JCPOA’s object and purpose
The legal framework for the snapback mechanism is premised on a functioning agreement grounded in peaceful dispute resolution, mutual restraint, and an operative IAEA verification regime. However, the military strikes of June 2025, carried out by Israel and the United States and actively condoned and praised by the E3, have irreparably destroyed this framework.
Most notably, the physical destruction of Iran’s declared and monitored nuclear sites has eliminated the very facilities those resolutions were designed to constrain and monitor. The IAEA reported “catastrophic and irreversible damage” to Iran’s enrichment capabilities, “effectively terminating” its ability to conduct verification activities under the JCPOA. The JCPOA’s core object and purpose – verifiable assurance of a peaceful program through monitoring and restraint – has been obliterated not by Iran, but by third-party military action endorsed by the E3. As the ICJ noted in Gabčíkovo-Nagymaros (para. 47), treaties may lapse when their “common object has disappeared.” In this context, invoking snapback to reimpose sanctions designed to restrain activities that have already been physically annihilated is not only detached from reality but constitutes a cynical and bad-faith manipulation of international legal mechanisms. The subject matter of the agreement and the resolutions linked to snapback has been nullified.
Conclusion
The E3’s legal capacity to invoke the snapback mechanism under the JCPOA’s Dispute Resolution Mechanism is legally extinguished due to their conduct following the June 2025 military strikes. Their material breaches of JCPOA obligations—including the duty of good faith under Article 26 of the Vienna Convention on the Law of Treaties (VCLT) and the commitment to peaceful dispute resolution under Section 36 of the agreement—combined with their tacit endorsement of grave violations of Article 2(4) of the UN Charter, a jus cogens norm, strip them of any credible standing. Moreover, their inconsistent legal posture compared to earlier positions estops them from claiming snapback rights, while their “unclean hands,” demonstrated by tacitly supporting actions that led to the destruction of the JCPOA’s verification architecture, further disqualify them from invoking its enforcement provisions. In addition, the physical annihilation of critical monitoring infrastructure constitutes both a fundamental change of circumstances under VCLT Article 62 and a case of supervening impossibility under Article 61, thereby nullifying the legal foundation for any snapback procedure. In light of these compounded breaches and altered circumstances, the E3 possess no viable legal pathway to trigger sanctions snapback under the JCPOA framework.
