The following post is by Drs. Tadesse Kebebew, Caroline Pellaton, and Mara Tignino. Kebebew is a Legal Researcher and Project Manager at the Geneva Water Hub, a joint center of the University of Geneva and the Geneva Graduate Institute; Pellaton is the Operations Director at the Geneva Water Hub; Tignino is Senior Lecturer at the Faculty of Law and the Global Studies Institute and Lead Legal Specialist of the Platform for International Water Law at the Geneva Water Hub. You can reach Dr. Tignino at Mara.Tignino [at] unige.ch.
How a ‘terror’ attack sparked a water dispute
Long regarded as one of the most resilient frameworks for transboundary water cooperation, the Indus Waters Treaty (IWT) signed in 1960 is now under acute strain amid escalating geopolitical tensions, marked by deepening mistrust, intensifying nationalist discourse and sustained militarisation. It was within this volatile context that on 22 April 2025, an armed group known as The Resistance Front carried out a deadly attack on a group of tourists in Pahalgam, located in Indian-administered Kashmir. The assault resulted in the deaths of at least 26 civilians and prompted immediate condemnation from Indian authorities, who attributed the attack to Pakistan-based militant support.
In the immediate aftermath, on 24 April 2025, India formally notified Pakistan of its decision to suspend the IWT. In its official communication, India appeared to cite two justifications for this decision – a fundamental change in circumstances since the treaty entered into force and breaches of treaty obligations by Pakistan. Specifically, India pointed to what it described as ‘sustained cross-border terrorism targeting the Indian Union Territory of Jammu and Kashmir’, asserting that these ongoing hostilities have generated serious ‘security uncertainties’ and thereby impaired India’s ability to fully utilise its entitlements under the treaty.
On 12 May 2025, Prime Minister Narendra Modi declared that ‘India’s water will flow for India’s benefit, it will be conserved for India’s benefit, and it will be used for India’s progress’, reiterating his longstanding position that ‘blood and water cannot flow together’. This stance was reinforced on 22 May 2025, when External Affairs Minister Subrahmanyam Jaishankar confirmed that India’s participation in the IWT would remain in abeyance until Pakistan ‘credibly and irreversibly’ ends its support for terrorism. These statements reflect a deliberate linking of transboundary water cooperation under the IWT to broader national security concerns.
A legacy of cooperation and disputes
The IWT, signed in 1960 under the auspices of the World Bank, is a rare example of resilient cooperation in a historically hostile relationship. It allocates the three eastern rivers (Ravi, Beas, Sutlej) to India and the three western rivers (Indus, Jhelum, Chenab) to Pakistan. Under the treaty, India was granted exclusive use of the three eastern rivers – Ravi, Beas and Sutlej, while Pakistan received rights over the three western rivers – Indus, Jhelum and Chenab. India retained limited rights to use the western rivers for non-consumptive purposes, such as hydropower, subject to specific design and operational constraints intended to protect downstream flows to Pakistan. In cases of disputes, the IWT establishes dispute resolution mechanisms comprising the Permanent Indus Commission, the resort to a neutral expert, and an arbitration procedure. India and Pakistan have already used all these mechanisms and currently, two disputes are under review by an arbitration tribunal and a neutral expert.
Despite armed conflicts (1965, 1971, Kargil 1999), military standoffs, and tensions, the IWT has stood firm for over six decades, serving as a lifeline for millions dependent on the Indus River basin. Cooperation over water has persisted, even as broader bilateral ties fractured. Nevertheless, the treaty has been tested by recurring disagreements over dam designs and water use. Notably, the Kishenganga Hydroelectric Project on the Jhelum River led to formal arbitration before the Permanent Court of Arbitration, which in its 2013 Final Award, upheld India’s right to divert waters but imposed minimum environmental flow requirements to safeguard Pakistan’s downstream interests. These and other disputes, including those over the Baglihar Dam, reveal the capacity of the treaty to address disputes within a clear legal and institutional framework. Its strong dispute-resolution clause allows the Parties to find common solutions despite the geopolitical and hydrological stress. More recently, concerns have grown over what Pakistan views as India’s efforts to reduce water cooperation to a zero-sum game, threatening the cooperative spirit that the IWT was designed to foster.
India’s suspension of the IWT
The announcement by the Government of India that the treaty would be ‘held in abeyance with immediate effect’ constitutes an unprecedented move in the treaty’s history and has since sparked a wave of intense legal debates (see here, here and here). India has sought to justify this decision by invoking the doctrine of ‘fundamental change of circumstances’ and alleging a material breach by Pakistan, specifically citing Pakistan’s alleged support for cross-border terrorism that jeopardizes its national security. While these concerns are of considerable political significance, their adequacy as legal grounds for a unilateral suspension of IWT is questionable.
Do the justifications cited by India meet the criteria of a ‘fundamental change of circumstances’ as understood in international treaty law? Can persistent cross-border terrorism and the associated security challenges be deemed a material breach sufficient to justify unilateral suspension? In the following sections, we scrutinize the legality of India’s suspension of the IWT from the standpoint of international treaty law, particularly as codified in the Vienna Convention on the Law of Treaties (VCLT) of 1969. Although India is not a party to the VCLT, its provisions are broadly recognized as reflective of customary international law (see the Gabcíkovo-Nagymaros case (Hungary/ Slovakia, 1997, para.46)) and thus applicable to the conduct of all states. This analysis evaluates India’s justifications against a tightly constrained legal framework for treaty suspension recognized in customary international law – operation of the treaty or mutual consent, impossibility of performance and fundamental change of circumstances.
Operation of the treaty or mutual consent
The VCLT sets out the foundational legal framework governing the conclusion, entry into force, application, suspension and termination of treaties. Article 26 of the VCLT enshrines the principle of pacta sunt servanda, which requires that treaties in force must be observed and performed in good faith by all parties. There are also legally recognized grounds to suspend a treaty in whole or in part. The first of such grounds is by the operation of the treaty (either expressly or by implication) or mutual consent of the parties involved (either during the conclusion of the treaty or afterwards) (see Articles 57-59). These provisions presuppose a mutual and voluntary decision by all treaty parties to suspend its application, whether partially or wholly.
However, the IWT contains no clause permitting unilateral suspension, and there is no evidence that Pakistan has provided explicit or implicit consent to such action. On the contrary, Pakistan has consistently maintained that the treaty remains fully in force and has actively sought third-party adjudication to ensure its continued implementation. As such, in the absence of any mutual agreement, India’s unilateral decision to suspend the treaty lacks a valid legal basis under these provisions. The essential element of reciprocal consent is absent, and therefore, this route does not provide India with a lawful justification for its actions.
Fundamental change of circumstances
India’s primary legal justification centres on the claim that there has been a fundamental change of circumstances since the treaty entered into force. Under Article 62 of the VCLT, the doctrine of rebus sic stantibus, allows for the termination or suspension of a treaty if an unforeseen and fundamental change of circumstances has occurred, radically transforming the obligations imposed by the treaty. While frequently invoked, this ground is rarely accepted in international practice and is interpreted restrictively to preserve the stability and continuity of treaty relations. The International Court of Justice (ICJ), in the Gabcíkovo-Nagymaros case, affirmed that ‘the negative and conditional wording of Article 62’ is a clear indication that the stability of treaty relations requires that ‘the plea of fundamental change of circumstances be applied only in exceptional cases’ (para. 104).
For such a claim to succeed, the alleged change must (1) have been unforeseen by the parties at the time of the treaty’s conclusion, (2) constitute an essential basis of their consent to be bound by the treaty, and (3) have radically altered the nature of the obligations still to be performed. In the Fisheries Jurisdiction case (United Kingdom v. Iceland, 1973), the ICJ underscored that only changes of circumstances that are ‘fundamental’ or those which constituted an essential basis of the consent of the parties to accept a treaty and which have resulted in a radical transformation of the extent of the obligations still to be performed, can be accepted as valid grounds (paras 36-38, & 41). In the Gabcíkovo-Nagymaros case, the ICJ reemphasized that this ground requires that the fundamental change of circumstances ‘radically transform the extent of the obligations’ to something essentially different from what is undertaken initially and that such changes ‘must have been unforeseen’ (para.104). Interestingly, it indicated that ‘new developments in the state of environmental knowledge’, arguably including climate change-related issues, cannot be said unforeseen (para.104).
These precedents underscore the ICJ’s insistence on strict adherence to the principle of good faith and stability of conventional law in international treaty relations and confirm that no party may unilaterally abrogate its obligations on the vague basis of changed political, social or environmental conditions.
In light of the foregoing, India’s claims in its official statement of 24 April 2025 of the ‘altered population demographics’ and ‘the need to accelerate the development of clean energy and other changes in the assumptions underlying the sharing of waters, do not constitute ‘fundamental change of circumstances’.
A material breach of treaty obligation
India’s second justification is the allegation that Pakistan has committed a material breach of the treaty by providing support to cross-border terrorism. Under Article 60 of the VCLT, a party to a bilateral treaty may suspend its obligations if the other party commits a material breach, defined as a violation of a provision essential to the treaty’s object or purpose.
This legal ground imposes a high threshold and is intended to balance the stability of treaty relations with flexibility in the face of serious violations. Crucially, the breach must pertain directly to the core provisions of the treaty itself, not to external political or security disputes. In this case, no evidence has been put forward that Pakistan has breached any substantive provisions of the IWT, which remains an agreement on water sharing in the Indus River Basin. Allegations of terrorism, while grave, fall outside the scope of the treaty and, therefore, cannot be construed as a material breach of its core provisions. Moreover, the IWT includes a detailed dispute resolution framework India was obligated to pursue before taking unilateral action. India’s bypassing of this process weakens the legal validity of its claim under Article 60.
Accordingly, India’s assertion that Pakistan’s alleged support for terrorism justifies suspending the treaty is legally unconvincing. Firstly, a terrorist incident, even if state-attributed, does not satisfy the threshold for suspension of a water-sharing treaty. This claim concerns political and security matters that do not alter the physical or institutional operation of the water-sharing arrangement. Secondly, according to the IWT itself, ‘the existence of any fact which, if established, might constitute a breach of this Treaty shall first be examined’ by the Permanent Indus Commission (Article XI). Thirdly, the treaty has already withstood armed conflicts and decades of hostile relations, which suggests that it operates independently of fluctuating bilateral tensions. Consequently, India’s position does not satisfy the stringent requirements of Article 62.
Moreover, even if India seeks to justify its suspension of the Indus Waters Treaty (IWT) as a lawful countermeasure under the law of state responsibility, namely, a temporary and unilateral non-performance of obligations in response to a prior internationally wrongful act (see Articles 49-54 of the Draft articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA)), we argue that the conditions set out in the ARSIWA are not met. Countermeasures involve a temporary derogation from treaty obligations and may be taken in response to violations of any international obligation by the other party, not necessarily one arising from the same treaty. On this basis, India could argue that Pakistan’s alleged breaches of other international obligations justify its actions.
However, countermeasures are strictly regulated under the ARSIWA. To be lawful, they must be proportionate, reversible and aimed at inducing compliance, not punishing the offending state. India’s abrupt and unilateral suspension of the IWT, particularly in the absence of prior notification or genuine efforts at dispute resolution, appears more punitive than corrective. Additionally, countermeasures must not interfere with obligations essential to the protection of fundamental human rights (Article 50, ARSIWA). Given that access to water is intrinsically linked to public health, food security and basic human survival, any disruption in water-sharing under the IWT risks crossing into unlawfulness, especially if it jeopardises drinking water or irrigation critical to affected populations.
Supervening the impossibility of performance
A further legal ground, though not explicitly raised by India, could be inferred from its communication – the supervening impossibility of performance. Article 61 of the VCLT permits termination or suspension only when the performance of the treaty becomes objectively impossible due to the permanent disappearance or destruction of an essential element necessary for performance. A commonly cited example of this ground is the ‘drying up of a river’, where such an event renders the performance of the treaty objectively impossible (Shaw, 2017, p. 719).
In the case of the IWT, the Indus River system and its tributaries have not changed and are not at risk of drying up. No objective impossibility, whether legal or physical, has been demonstrated. Besides, neither party has asserted that performance under the IWT has become impossible. India’s security concerns, even if genuine, pertain to unrelated security and geopolitical issues rather than any factual impediment to fulfilling the treaty’s core obligations.
Continuing obligations under international water law (IWL)
Even assuming, for argument’s sake, that India could validly suspend or withdraw from the IWT, it would still be bound by general principles of international water law. These are most clearly articulated in the 1997 UN Convention on the Law of the Non-Navigational Uses of International Watercourses. While neither India nor Pakistan is a party to the Convention, its key principles – equitable and reasonable utilization, the obligation not to cause significant harm and the duty of prior notification – are widely recognized as customary international law (see e.g., here, pp.14 & 16). These obligations ensure that riparian states cooperate in good faith and do not undertake actions that would materially harm co-riparian rights.
Hence, India’s suspension of treaty obligations does not place it outside the scope of international legal scrutiny. As an upstream riparian state, India has a duty to manage its water resources in a manner that does not significantly harm Pakistan’s rights. A unilateral disruption of river flows or suspension of data-sharing mechanisms would likely breach these customary obligations, subjecting India to international legal accountability.
A case for a peaceful dispute resolution
Under international law, states must resolve their disputes peacefully (UN Charter, Articles 33-38). Reflecting this principle, the IWT incorporates a structured three-tiered dispute resolution mechanism: the Permanent Indus Commission, recourse to a Neutral Expert, and adjudication by a Court of Arbitration. Of particular importance is the mandate given to the Permanent Indus Commission, i.e., ‘to establish and maintain co-operative arrangements for the, implementation of this Treaty, to promote co-operation between the Parties in the development of the waters of the Rivers’ (Article VIII, IWT).
India’s previous engagement in the Kishenganga arbitration clearly illustrates that treaty-related disputes can be addressed effectively through these mechanisms, without resorting to suspension or unilateral measures. Currently, another dispute is pending before an Arbitration Tribunal. The dispute was brought by Pakistan in 2016 and concerns the construction of several hydroelectric plants on the Indus, Jhelum and Chenab rivers and their tributaries. Although India has decided not to appear before the Tribunal and considered a neutral expert must address the questions placed before the judicial body, the Arbitral Tribunal declared itself as competent to decide on the questions raised in Pakistan’s Request for Arbitration.
Conclusion
This analysis finds that India’s suspension of the IWT lacks a valid legal basis under international law. None of the recognized grounds – mutual consent, impossibility of performance, or fundamental change of circumstances – apply to the case at hand, making the action incompatible with the principle of pacta sunt servanda and broader international law principles and norms. Unilateral suspension risks weakening longstanding institutional cooperation and unravelling one of the few enduring mechanisms of India–Pakistan engagement. Rather than suspending or disregarding the treaty, a more constructive path lies in allowing the Commission to incorporate new environmental standards in the application and interpretation of the provisions of the Treaty.
As IWL continues to develop and refine, water must be used by India and Pakistan as a tool of rapprochement and dialogue and not as an additional means of division. Preserving and reinforcing the IWT and its Permanent Indus Commission offers a vital opportunity for dialogue and shared prosperity in a region. A recommitment to the treaty is not only legally necessary, but geopolitically urgent.
