Bombs for Bargains: Can a Treaty Imposed on Iran Through Military Coercion Be Valid Under International Law?

[Heybatollah Najandimanesh, associate professor of international law at Allameh Tabatabaei University, Tehran, Iran]

Introduction

Can a treaty concluded under sustained military pressure ever constitute a valid expression of state consent? This question lies at the heart of Article 52 of the Vienna Convention on the Law of Treaties (VCLT), which provides that a treaty is void if its conclusion has been procured by the threat or use of force in violation of the UN Charter. While the provision is widely regarded as a cornerstone of the Charter-based legal order, its practical application remains uncertain. International negotiations frequently take place under conditions of severe inequality, armed conflict, and political pressure, making it difficult to determine the point at which pressure becomes legally cognizable coercion. This post examines a legally framed factual scenario concerning the validity of a possible future agreement between Iran and the United States following a prolonged period of military confrontation and coercive diplomacy. At the time of writing, the parties have reportedly reached only a preliminary framework designed to facilitate negotiations over a final settlement during a sixty-day period. The legal status of any eventual agreement therefore remains an open question.

The Background: From the JCPOA to Coercive Diplomacy

The United States has consistently maintained that its principal dispute with Iran concerns the latter’s nuclear program. In this context, the Joint Comprehensive Plan of Action (JCPOA) was concluded in 2015. Following a change of administration, the United States withdrew from the agreement in 2018 and adopted a “maximum pressure” policy based on extensive economic sanctions aimed at inducing Iran to accept a revised arrangement. In June 2025, while negotiations between Iran and the United States were ongoing, Israel launched military strikes against Iran with the reported approval and encouragement of the United States. In the final phase of this escalation, the United States also struck Iran’s peaceful nuclear facilities. These actions were publicly linked to efforts to increase pressure on Iran to reach a new agreement, although no settlement was achieved. Subsequently, in December 2025, efforts by the United States and Israel to support internal unrest in Iran with the stated objective of facilitating regime change did not succeed. Thereafter, on 28 February 2026, a large-scale military operation was initiated against Iran involving the United States, Israel, and several regional states, with stated objectives including regime change and the establishment of a new negotiating framework. Following the inability to achieve these objectives, a ceasefire was declared. In the aftermath, United States naval forces established a maritime blockade in the region. Reports further indicate that certain Iranian infrastructure facilities were struck in April, and that additional attacks were carried out thereafter. Following the ceasefire, U.S. officials stated that negotiations were underway for a “very good deal” with Iran, while simultaneously warning that refusal to accept U.S. conditions could lead to further attacks on Iran’s core infrastructure, including refineries, bridges, steel industries, and power plants, as well as renewed military operations. Against this background, the central question is whether, in the event that a treaty is concluded under conditions of prolonged military action, naval blockade, and explicit coercive threats, it would be legally valid under Article 52 of the 1969 Vienna Convention on the Law of Treaties (VCLT) or whether it would be void ab initio as a treaty procured through the threat or use of force in violation of the UN Charter.

Article 52 and the Charter-Based Structure of Consent

Article 52 VCLT links treaty validity directly to the UN Charter prohibition on the threat or use of force. The legality of treaty consent cannot be separated from the legality of the means by which that consent is produced. The provision reflects the transition from classical international law, in which war and coercion could generate legal rights, to a Charter-based order founded on the prohibition of unlawful force. Within this framework, recognizing treaties concluded through unlawful coercion would undermine the normative structure established by Article 2(4) of the UN Charter. Article 52 is grounded in the principle ex injuria jus non oritur: unlawful acts cannot generate valid legal rights or obligations. Just as territorial acquisition achieved through force is denied legal recognition, treaty obligations cannot arise from consent procured through unlawful coercion. The provision is therefore not merely concerned with defective consent. It functions as a structural safeguard of the Charter order and is closely linked to the peremptory norms reflected in Article 53 VCLT. Its underlying rationale is straightforward: unlawful force cannot be converted into lawful outcomes through diplomatic agreement. In this sense, invalidity is not simply a consequence of impaired will but also of incompatibility with the fundamental norms of the international legal system. At the same time, Article 52 does not encompass every form of pressure. The decisive distinction is between ordinary political or strategic pressure and coercion involving unlawful force that is causally decisive in producing consent. The International Law Commission and subsequent jurisprudence, including the Fisheries Jurisdiction cases, support the view that treaties procured through such force are void as a matter of customary international law.

The Threshold of Coercion

The most difficult issue under Article 52 is determining when pressure crosses the line into legally relevant coercion. International negotiations rarely occur in conditions of complete equality. States routinely bargain under economic pressure, political isolation, security threats, or adverse military realities. Article 52 does not invalidate treaties merely because one party negotiates from a position of weakness. The drafting history of the VCLT confirms that the provision is confined to treaties procured by the threat or use of force contrary to the UN Charter. Proposals to extend the rule to economic or political coercion were deliberately rejected. Consequently, the provision targets a narrower category of conduct: unlawful military force employed as an instrument for obtaining treaty consent. The decisive issue is a direct causal link between force and consent.

The distinction can be illustrated through simple examples. Suppose State A defeats State B in an armed conflict lawfully conducted in self-defence and the parties subsequently conclude a peace treaty defining their future relations. The treaty is not invalid merely because State B negotiated under difficult circumstances or wished to avoid renewed hostilities. Military realities may explain why a state enters negotiations, but they do not necessarily amount to coercion under Article 52. By contrast, consider a situation in which State A unlawfully attacks State B and openly conditions the cessation of military operations upon acceptance of specific treaty terms. If State A threatens further strikes unless those terms are accepted, military force ceases to be mere background context and becomes an instrument for shaping consent itself. In such circumstances, the treaty may be regarded as having been procured by coercion. The decisive inquiry is therefore not whether negotiations occur under pressure but whether unlawful force exerts a sufficiently direct and substantial influence on the formation of consent. The requirement of procurement establishes this causal link and distinguishes coercion prohibited by Article 52 from the ordinary inequalities that characterize much of international diplomacy.

U.S. Official Statements and the Coercive Framing of Negotiation

Within this framework, statements made by senior political and military officials acquire legal significance not because of their political content but because they may illuminate the relationship between force and consent. Publicly reported statements by President Trump and members of his administration have at times suggested a linkage between Iran’s willingness to reach an agreement and the continuation or escalation of military pressure. When Trump was asked what he would do if Tehran did not make a deal, he reportedly responded: “We’ll bomb the s–t out of them tomorrow.” References to the consequences of non-compliance, warnings of additional military action, and assertions that further strikes may follow absent political concessions potentially raise questions that extend beyond ordinary diplomatic bargaining. Taken together, such statements may provide evidence that military pressure was not merely contemporaneous with negotiations but formed part of a broader strategy aimed at influencing the terms or outcome of a potential agreement. International law does not invalidate treaties simply because negotiations occur in the shadow of military power. States frequently negotiate while facing security threats, ongoing conflicts, or adverse strategic circumstances. Article 52 is not concerned with pressure in the abstract.

Rather, the relevance of such statements lies in their evidentiary value. They may assist in determining whether force is being used as a mechanism for shaping consent itself. The crucial inquiry is whether military action and diplomatic negotiations remain analytically distinct or whether force has become integrated into the bargaining process in such a way that consent can be said to have been procured through coercion.

Procurement and the “Decisive Influence” Standard

The concept of “procurement” under Article 52 requires more than the mere existence of military pressure or prior unlawful force. The provision does not automatically invalidate treaties concluded in such circumstances. Rather, unlawful force must be shown to have procured consent in a legally meaningful sense. The ILC rejected both a strict “but-for” test and a requirement that coercion be the sole cause of consent, recognizing that treaty formation is often influenced by multiple political, economic, and security factors. The more persuasive interpretation focuses on whether unlawful force exerted a “decisive influence” on the formation of consent. The phrase “procured by” supports this approach, requiring more than incidental involvement of force but not exclusive causation. Where coercion materially shapes acceptance of a treaty, the causal threshold may be satisfied even if other factors are also present. In the Iranian context, the key issue is therefore whether military pressure can be shown to have materially shaped consent and thus be legally attributable to coercion.

Are Peace Settlements Excluded from Article 52?

Article 52 does not categorically exclude peace treaties from its scope. The mere fact that an agreement follows armed conflict does not render it invalid. As confirmed by the ILC, the provision applies only where a treaty is procured by unlawful force contrary to the UN Charter. Peace settlements following lawful self-defence or Security Council-authorized action are therefore not affected simply because they arise after conflict. However, describing an agreement as a peace treaty does not shield it from scrutiny. If unlawful force played a decisive role in securing consent, Article 52 may apply. The key inquiry is whether force merely formed the background context of negotiations or actually procured consent through unlawful coercion.

Void Ab Initio and the Legal Consequences of Coercion

Article 52 provides that treaties procured through unlawful force are void ab initio. Their invalidity is automatic and operates from the moment of conclusion, rather than being merely voidable or dependent on judicial confirmation. Once the conditions of Article 52 are satisfied, the treaty has no legal effect from the outset. This consequence reflects the role of Article 52 in safeguarding the integrity of the UN Charter system and preventing unlawful force from generating legal rights through treaty-making.

Accordingly, invalidity arises by operation of law and is not limited to protecting the interests of the coerced state. A treaty concluded under coercion cannot be retroactively validated through subsequent acceptance or acquiescence; only a new agreement concluded under lawful conditions may create binding obligations. Moreover, coercion may originate not only from a treaty party but also from third states or other actors whose conduct procures the agreement. The doctrine of absolute nullity thus serves as a structural safeguard against the normalization of coercive treaty outcomes.

Article 52 Beyond Bilateralism

Article 52 possesses a systemic dimension that extends beyond bilateral treaty relations. emphasizes that the prohibition of the use of force under the UN Charter protects interests of the international community as a whole, rather than merely reciprocal state obligations. From this perspective, invalidity under Article 52 cannot be fully understood through a purely consent-based bilateral framework. The principle ex injuria jus non oritur supports this broader view: unlawful acts should not generate legal entitlements, whether in territorial acquisition or treaty obligations. The common objective is to prevent fundamental violations of international norms from producing legal effects. The systemic function of Article 52 is therefore to preserve the integrity of the Charter order. If treaties procured through unlawful force were widely accepted or normalized, this could indirectly weaken the effectiveness of Article 2(4) by allowing states to achieve through diplomatic instruments what they are prohibited from achieving through military action. Although international law has not yet developed a fully articulated doctrine on third-state recognition of coercively procured treaties, the underlying logic of Article 52 suggests concerns that extend beyond the immediate parties and relate to the stability of the normative system itself.

Conclusion

Article 52 VCLT provides that a treaty is void if its conclusion is procured by the threat or use of force contrary to the UN Charter. Grounded in the principle ex injuria jus non oritur, the provision serves not only to protect state consent but also to preserve the integrity of the post-1945 international legal order by preventing coercive treaty-making. Article 52 does not address mere political pressure, inequality, or adverse bargaining conditions, nor does the existence of unlawful force automatically invalidate a treaty. The decisive issue is causation: whether unlawful force exerted a decisive influence on the formation of consent. Determining this requires a contextual assessment of negotiating conduct, official statements, and the substantive content of the agreement. Contemporary practice demonstrates the difficulty of distinguishing lawful bargaining under pressure from legally cognizable coercion. In the Iranian context, the validity of any agreement ultimately depends on whether consent can be legally attributed to unlawful coercion. Only where this threshold is satisfied would the treaty be void ab initio.