The recent deterioration in India-Pakistan relations has once again brought the Indus Waters Treaty (IWT) of 1960 to the forefront of international legal and strategic debate. Following the Pahalgam terrorist attack, India announced that it would place the Treaty in abeyance and linked future cooperation to Pakistan’s commitment to ending cross-border terrorism. Pakistan responded with strong rhetoric, characterising India’s move as “weaponizing water” and even suggesting that interference with its allocated share would amount to an act of war. These developments raise a profound legal and political question: Can water become a weapon in international law? The answer is more complex than either political narrative suggests. International law neither grants an upstream State unlimited sovereignty over transboundary rivers nor gives a downstream State an absolute right to uninterrupted flows. Instead, it seeks to balance competing rights through treaties, customary international law, and the principles of cooperation and equitable utilisation.

The Treaty and the Present Legal Dispute

The Indus Waters Treaty remains one of the most remarkable examples of international water diplomacy. Signed on 19 September 1960 after nearly a decade of negotiations under World Bank auspices, it allocated the three Eastern Rivers—Ravi, Beas and Sutlej—to India, while assigning the Western Rivers—Indus, Jhelum and Chenab—primarily to Pakistan. India retained carefully defined rights over the Western Rivers for domestic use, limited irrigation, navigation, and run-of-the-river hydroelectric projects. Despite wars in 1965, 1971 and 1999, repeated terrorist attacks, and prolonged political hostility, the Treaty survived for more than six decades, demonstrating the resilience of law even amidst geopolitical conflict. The central issue today is whether India can legally stop or substantially reduce the flow of water to Pakistan. The legal position is often misunderstood. While India undoubtedly possesses rights as the upstream State, those rights are accompanied by corresponding legal obligations. The Treaty is a binding international agreement, and Article III obliges India to allow the waters of the Western Rivers to flow, subject only to the limited uses expressly permitted by the Treaty. Consequently, India cannot simply divert, impound or permanently block these rivers beyond the limits agreed in 1960.

Treaty Law and the Vienna Convention

Equally important is the fact that the Treaty contains no unilateral exit clause. Unlike many modern international agreements, it does not expressly permit either party to suspend or terminate the Treaty acting alone. Pakistan therefore argues that India remains legally bound unless both States mutually agree to amend the Treaty or unless its termination can be justified under general international law. India, however, contends that persistent cross-border terrorism and dramatically changed circumstances have fundamentally altered the basis upon which cooperation under the Treaty was originally envisaged. The present dispute also raises important questions under the Vienna Convention on the Law of Treaties (1969). Although India is not a party to the Convention, many of its provisions reflect customary international law. Article 60 permits suspension of treaty obligations in cases of a material breach, leading some scholars to argue that persistent cross-border terrorism may have undermined the Treaty’s foundation of peaceful cooperation—a view Pakistan rejects. Article 62, concerning a fundamental change of circumstances, has also been invoked considering climate change, altered hydrology, and evolving security concerns. Whether these factors legally justify suspending or renegotiating the Treaty remains a contested question.

Principles of International Water Law

International water law offers additional guidance. Modern international law rejects the doctrine that the State through which a river originates enjoys absolute ownership over its waters. Equally, it rejects the notion that downstream States possess unlimited rights irrespective of upstream development needs. Instead, several well-established principles govern international rivers. International water law is founded on four core principles. First, equitable and reasonable utilisation requires all riparian States to enjoy a fair, though not necessarily equal, share of a shared river’s benefits, taking into account geography, population, development, and environmental needs. Second, the No Significant Harm Principle prohibits upstream States from causing serious harm to downstream States. Third, States have a duty to cooperate through data sharing, prior notification of major projects, and continuous dialogue. Finally, disputes should be resolved peacefully. These principles are reflected in the 1997 UN Watercourses Convention, the Helsinki Rules (1966), the Berlin Rules (2004), and customary international law.

Water as a Weapon and Dispute Resolution

International law discourages the weaponisation of water because it is indispensable for drinking, agriculture, public health, energy, and human survival. Deliberately restricting water to inflict humanitarian or economic harm may violate the principles of good faith, international humanitarian law, and, during armed conflict, the law of armed conflict. However, lawful regulation of river flows under a treaty is fundamentally different from using water as a political or military weapon. The Treaty establishes a comprehensive dispute-resolution mechanism. Technical issues are first considered by the Permanent Indus Commission; engineering disputes may be referred to a Neutral Expert; and disputes concerning the Treaty’s interpretation or application may be submitted to a Court of Arbitration. In its June 2025 Supplementary Award, the Hague Court of Arbitration reaffirmed its jurisdiction over the Kishanganga and Ratle disputes despite India’s decision to place the Treaty in abeyance. India rejected the Award, maintaining that the Court was improperly constituted and lacked jurisdiction, while Pakistan continues to regard its decisions as binding. The controversy therefore extends beyond water allocation to encompass competing interpretations of the Treaty’s dispute-resolution framework and the authority of international adjudicatory mechanisms.

Conclusion

The Indus Waters Treaty remains one of the most successful examples of international water diplomacy, but it now faces its most serious legal and political challenge. The present controversy is not merely about water allocation; it raises fundamental questions concerning treaty obligations, national security, terrorism, and the future development of international water law. While India possesses legitimate rights as an upstream State, those rights are accompanied by corresponding legal obligations. Equally, Pakistan’s rights under the Treaty exist within an evolving framework of international law and changing geopolitical realities. Ultimately, any lasting solution must emerge through dialogue, mutual consent, and respect for international law rather than unilateral action or political rhetoric. The future of the Indus Waters Treaty will therefore depend not only upon legal interpretation but also upon the willingness of both countries to preserve one of the world’s most enduring frameworks for cooperation over shared natural resources. / DAILY WORLD /

( Prof Nehaluddin Ahmad, LL.D. Professor of Law, Sultan Sharif Ali Islamic University (UNISSA), Brunei, Email: ahmadnehal@yahoo.com )