Despite its obvious failure to prevent a new outbreak of hostilities in the short term, the Memorandum of Understanding (“MOU”) signed by the United States and Iran on June 17, 2026, represents an important inflection point in the long-standing conflict between the two powers. While the MOU was dismissed by many commentators, even before the ink was dry, as a stopgap measure containing vague, ambiguous, and perhaps even non-binding commitments, in fact, it has reshaped the parameters of the conflict. A clear example is the struggle over the Strait of Hormuz. The MOU, and the divergent readings of it, have influenced the justifications or rationales each side maintains for returning to war. At the same time, the non-compliance that followed rather swiftly upon its signing does not preclude the MOU from having other normative effects, including on future negotiations to return to peace; there is literature that suggests that even peace agreements that fail to end the fighting nevertheless reduce the overall lethality of the conflict.
As I shall point out in this Article, discussion of the MOU, even in the “expert” think tank world, has been marred by misunderstandings, including, in some cases, basic ignorance, concerning the detailed provisions of the MOU, for example, the notion that the Agreement is non-binding or that all its obligations depend upon a subsequent final agreement. In this Article, I aim to explicate the terms of the MOU, pointing not only to its weaknesses but also to its innovative features, which might subsist as elements of a more comprehensive future agreement. As will be explained, ambiguities or vagueness in the MOU, such as concerning the final resolution of control over the Strait of Hormuz, may have contributed to the resumed hostilities of mid-July, but this does not mean that ambiguity in general is something to be avoided in peace agreements, or that all usage of ambiguity, vagueness, or incompleteness of obligations (“gaps”) in the MOU was unjustifiable.
The MOU has been dismissed on three grounds: that it is not binding; that its terms are too vague; and that the resumption of hostilities has rendered it dead. None survive examination. It is a binding international agreement. Its ambiguities are in large part deliberate. And it has not been terminated but suspended, with a core of obligations that neither party is free to shed. Whether the parties are complying with the MOU is the wrong question to be asking at this time. The right question is what it has already done and what it may continue to do.
This Article is divided into four parts. Part I provides the overall context, surveying U.S.-Iran relations from the Cold War to the present, with particular focus on the more recent strife over Iran’s nuclear program and U.S. sanctions that led up to the hostilities of 2025 and 2026, hostilities which the MOU was intended to end. Part II looks at the nature and structure of the obligations in the MOU, addressing whether it is “binding” under international law and its two-fold character as an interim peace deal and as a blueprint for future negotiations, including those concerning Iran’s nuclear program.
Part III is a textual legal analysis of the MOU, read in light of its context and other relevant international agreements and norms, including the recent U.S.-Israel-Lebanon Framework, the United Nations Convention on the Law of the Sea (“UNCLOS”), and the rules on the use of force according to customary international law and U.N. Charter rules. This part also addresses how controversy over the meaning of certain provisions of the MOU feeds into the continuing conflict and how that controversy might be resolved in an ongoing process of negotiations.
Part IV examines the broader impact of the MOU, beyond the question of whether a return to compliance or implementation can be achieved in the short term. The MOU may have established certain baselines or principles that are likely to be a starting point for any new effort at a negotiated settlement. More generally, it can be seen as an inflection point in the ongoing U.S.-Iran relationship, in some respects a reflection of how fraught it is (the need for ambiguity or agreeing to disagree) but also the hope for a better, if distant, future (the plan for a US$300 billion reconstruction development plan for Iran).
Recommended Citation: Robert Howse, “More Honored in the Breach Than the Observance”: A Legal and Strategic Analysis of the Islamabad Memorandum of Understanding Between the United States and Iran, 50 Fordham Int’l L.J. 169 (2026).