The Indus Water Treaty (IWT), signed in 1960 and mediated by the World Bank, is a key water-sharing agreement between India and Pakistan. The Treaty allocates the use of the Indus River system, which includes six rivers flowing through the region. It allocates the Western Rivers (Indus, Jhelum, Chenab) to Pakistan and the Eastern Rivers (Ravi, Beas, Sutlej) to India. The Treaty is considered one of the most successful transboundary water-sharing agreements, as it has survived various political and military tensions between the two neighbouring nations. However, on 25 January 2023, India issued a notice to Pakistan seeking modification of the Treaty, citing Pakistan’s alleged intransigence as the primary concern. Subsequently, on 30 August 2024, India issued another notice, highlighting fundamental and unforeseen changes in circumstances as grounds for reviewing and modifying the Treaty. These notices raise significant concerns regarding their potential legal implications for the treaty. This insight delves into the legal analysis of the notices by examining the relevant provisions of international law and customary norms. The notices sent by India to Pakistan are merely a precursor to a negotiation process and do not unilaterally modify the Treaty. Tensions arose between the two countries over the design features of the Kishanganga (330 MW) and Ratle (850 MW) hydroelectric power plants located in India on tributaries of the Jhelum and Chenab Rivers. While the Treaty permits India to build hydroelectric facilities on these rivers, it requires compliance with design constraints and Pakistan’s approval. In 2016, Pakistan approached the World Bank, requesting the formation of a Court of Arbitration (CoA) to address its concerns over the power plants’ designs. India, however, insisted on appointing a Neutral Expert. To settle such disputes, the treaty establishes a comprehensive framework through the Permanent Indus Commission (PIC), which consists of a commissioner from each country. It categorises issues into three distinct levels: “questions” to be addressed by the Commission, “differences” to be resolved by a Neutral Expert, and “disputes” to be referred to as a CoA. This structured approach ensures that disagreements regarding the usage of shared rivers are systematically handled. The notices sent by India to Pakistan are merely a precursor to a negotiation process and do not unilaterally modify the Treaty. However, the countries remain divided on which dispute resolution process to follow. In response, the World Bank initiated both processes simultaneously. However, India chose not to participate in the CoA proceedings, and in 2023, it issued a formal notice to Pakistan seeking to modify the Treaty. From India’s perspective, Pakistan has bypassed the Treaty’s graded dispute resolution mechanism, constituting a material breach of the agreement. Furthermore, India contends that the World Bank, under persistent pressure from Pakistan, initiated two parallel dispute resolution processes-the CoA and the Neutral Expert – which risks producing conflicting outcome, which can potentially complicate the resolution of the issue. On the other hand, Pakistan asserts that the hydroelectric power plants being constructed by India violate the Treaty, arguing that this issue constitutes a “dispute” rather than a mere “difference”. Pakistan contends that the design conflict is not solely a technical matter but also requires interpretation of the Treaty. Therefore, referring the matter to the CoA rather than a Neutral Expert, who is limited to technical assessments, is crucial. In contrast, the CoA addresses both legal and technical aspects. As a result, Pakistan maintains that the CoA is the appropriate forum for resolving this issue, as stipulated by the Treaty. In response to India’s first notice, Pakistan’s Attorney General’s office confirmed that on April 5, 2023, Pakistan formally replied, expressing its willingness to address New Delhi’s concerns. Pakistan proposed that these discussions should occur within the framework of the PIC, demonstrating its commitment to resolving the matter through dialogue while upholding the Treaty’s provisions. On 30 August 2024, India issued another notice to Pakistan, citing ‘fundamental and unforeseen circumstances’ that necessitate a reassessment of the IWT. India’s concerns include population demographic shifts, environmental challenges and the ongoing impact of cross-border terrorism. In response, Pakistan expressed its willingness to engage in discussions. Foreign Office Spokesperson Mumtaz Zahra Baloch clarified Pakistan’s position, emphasising the desire to address India’s concerns through the existing framework of IWT. It is essential to understand that India’s notice or request for modification does not ipso facto annually amend or modify the Treaty. The Treaty itself provides a framework for modification under Article XII. It explicitly states that modification or alteration cannot occur without the agreement of both parties. Therefore, any modification to the IWT must be negotiated, drafted, and ratified by both countries to have legal standing. The Treaty’s structure ensures that no unilateral modification is possible. Regarding annulment, customary international law supports the view that treaties of indefinite duration, such as the IWT, cannot be unilaterally terminated by one party without violating international law. Any such withdrawal would not only breach the terms of the Treaty but also constitute a gross violation of international law, as treaties of this nature are binding unless both parties agree to terminate them. Regarding India’s claim that Pakistan has materially breached the Treaty, this can be assessed under Article 60(3) of the Vienna Convention on the Law of Treaties (VCLT). Article 60(3) defines a material breach as: “(i) a repudiation of the treaty not sanctioned by the present Convention; or (ii) a violation of a provision essential to the accomplishment of the object or purpose of the treaty.” In this context, Pakistan’s decision to pursue the CoA over a Neutral Expert does not meet this definition. While the choice of dispute resolution mechanism is contested, it does not violate any provision essential to fulfilling the Treaty’s objectives. Therefore, the issue remains a procedural disagreement rather than a breach of the Treaty’s core provisions. Moreover, in its second notice, India’s claim regarding fundamental changes in circumstances can be addressed through dialogue at the PIC. However, India cannot use these claims as grounds for withdrawal from the treaty. Under Article 62(1) of the VCLT, the principle of pacta sunt servanda – the obligation to uphold treaties – prevails, even if unforeseen circumstances arise, unless the treaty’s provisions become an undue burden on one of the parties. Currently, there is no evidence that these circumstances have created such a burden on either party. The notices sent by India to Pakistan are merely a precursor to a negotiation process and do not unilaterally modify the Treaty. Both nations must uphold their international responsibilities and collaborate within the IWT framework to address their concerns. This landmark agreement on transboundary river systems has withstood numerous challenges and should not be altered or annulled based on political changes or personal preferences. It is essential that India and Pakistan honour their commitments and work together to preserve the Treaty’s integrity, ensuring continued cooperation and stability in their bilateral relations. The writer is a freelance columnist.