• With a special focus post-Pahalgam attack and India’s moves to stop the water flow under the Indus Waters Treaty 

The Indus Waters Treaty (IWT), signed in 1960 between India and Pakistan under World Bank auspices, is one of the most successful and enduring water-sharing agreements in the world. 

It has survived wars, political crises, and diplomatic standoffs between the two countries. The treaty’s key achievement is its precise division of river waters and its dispute resolution mechanisms, which have kept water-related cooperation insulated from broader geopolitical tensions. However, recent developments – especially the April 2025 terrorist attack in Pahalgam, Jammu and Kashmir – have tested the resilience of this framework.

The Pahalgam attack was an attack on tourists by five armed terrorists near Pahalgam in the Indian-administered Jammu and Kashmir in which 26 civilians were killed on 22 April. This attack was attributed by the Indian authorities to a Pakistan-based extremist group. This marked a significant escalation in cross-border tensions. In its aftermath, the Indian Government made strong political statements about re-evaluating the IWT. Indian Prime Minister Narendra Modi asserted: “Not a single drop of water will flow to Pakistan that rightfully belongs to India” and India promptly announced a review of existing water-sharing arrangements. The move sparked intense legal and diplomatic debate over whether India could lawfully halt or reduce water flows to Pakistan under the treaty.

What is the legality of India's actions following the Pahalgam attack, particularly its threat to stop water flows and expedite hydropower and storage projects. It must be evaluated based upon the provisions of the IWT itself, the general principles of international treaty law, and the norms of trans-boundary water governance as to whether India’s post-attack water diplomacy is consistent with international law or risks undermining the very foundation of the treaty.

The structure and purpose of the IWT 

The IWT allocates the six rivers of the Indus Basin between India and Pakistan; the eastern rivers (Ravi, Beas, Sutlej/Satluj) are for India’s unrestricted use, while the western rivers (Indus, Jhelum, Chenab) are primarily reserved for Pakistan, with limited allowances for Indian use. Articles II and III spell out these entitlements. India is permitted non-consumptive uses of the western rivers, including hydropower generation, navigation, and limited irrigation, provided that they do not harm Pakistan’s share.

The treaty’s annexures – particularly Annexure D – permit India to build run-of-the-river hydroelectric projects on the western rivers, subject to strict technical criteria. These include provisions regulating the reservoir capacity, the drawdown levels, and design-related constraints to avoid the manipulation of water flows. Additionally, Article VIII mandates continuous data sharing and technical cooperation via the Permanent Indus Commission, and Annexures F and G provide structured mechanisms for dispute resolution, including third-party arbitration and expert determination.

While these provisions were designed to be resilient and apolitical, the events following the Pahalgam attack saw India signaling a shift in approach. Indian officials declared their intent to maximise the use of its entitled water share and minimise the ‘unutilised flow’ into Pakistan. Projects such as the Ujh Multipurpose Project, the Shahpur Kandi Dam, and the Pakal Dul Dam were prioritised and linked explicitly to the Government’s post-attack response. Though these projects technically fall within India’s rights under the IWT, the linkage to a security incident raises questions about whether India’s actions are rooted in legal entitlement or political retaliation.

Indian hydroelectric projects and treaty interpretation 

India’s hydroelectric development on the Indus system has historically been a source of contention. Projects like the Baglihar Dam and the Kishanganga Hydroelectric Project faced legal challenges from Pakistan, with mixed outcomes at the level of neutral experts and the Permanent Court of Arbitration. In both cases, India’s general right to construct run-of-the-river facilities was upheld, but with strict compliance-related requirements. These precedents affirm that legality under the IWT hinges not on political context but on technical adherence to treaty terms.

However, the aftermath of the Pahalgam attack saw a qualitative shift in India’s rhetoric and pace of development. Projects on the eastern rivers, such as Shahpur Kandi and Ujh, were presented as instruments of strategic retribution. India emphasised that substantial volumes of water from the eastern rivers were flowing into Pakistan unused, and that this situation would no longer be tolerated. Plans were announced to complete these projects swiftly, aiming to reduce what was described as ‘unintentional water aid’ to Pakistan.

While these actions involve water legally allocated to India, the underlying intent expressed by Indian policymakers and the media introduces concerns under international law. The principle of good faith, as required by Article 26 of the Vienna Convention on the Law of Treaties, obligates states to perform treaty duties without ulterior motives that contradict a treaty’s spirit. India’s post-Pahalgam positioning – framing lawful development as retaliation – may not violate the IWT per se but does risk undermining its normative and cooperative foundations.

Int’l water law and the treaty’s binding nature 

Though the IWT is a bilateral treaty, its interpretation must be situated within the broader framework of international water law, particularly the 1997 United Nations (UN) Watercourses Convention (Convention on the Law of the Non-Navigational Uses of International Watercourses), which codifies global norms like equitable and reasonable utilisation, no significant harm, and cooperation. India is not a party to this Convention, but the principles it articulates reflect customary international law applicable to transboundary river systems.

Following the Pahalgam attack, India’s threat to stop or reduce flows to Pakistan – even if limited to its own allocated rivers – could have downstream effects and transgress the no-harm principle if not executed with care. The principle of proportionality also demands that retaliatory or defensive measures not exceed what is necessary. While using water entitlements is not inherently unlawful, doing so as a form of pressure undermines the ethos of cooperative river management and sets a dangerous precedent for treating water as a strategic weapon.

Furthermore, the IWT contains its own dispute resolution mechanisms in Articles IX to XII, which must be respected before taking unilateral action. International jurisprudence, such as in the Gabcíkovo-Nagymaros Project (Hungary/Slovakia) International Court of Justice 1997 case, confirms that even in cases of national security or a fundamental change of circumstances, states must act within legal frameworks and in consultation with treaty partners. India’s public signaling post-Pahalgam could be interpreted as bypassing these requirements, jeopardising both the stability of the treaty and the principles of international law.

Legality of India’s actions post-Pahalgam 

India’s post-Pahalgam water policy has involved two major strands: (1) Maximising its use of eastern river waters that formerly flowed unused into Pakistan, and (2) accelerating hydroelectric and storage projects on the western rivers under its limited rights. On paper, these actions are not in breach of the IWT if executed within technical and procedural limits. However, the context – using these measures as a response to a terrorist attack – has sparked controversy over their legality and intent.

Indian statements following the attack, including the declaration that "not a single drop of water will go to Pakistan" were seen by many as attempts to weaponise water. This rhetoric contradicts the IWT’s goal of peaceful and cooperative management. Even if India refrains from violating the specific provisions of the treaty, using water as an instrument of coercion violates broader principles of international environmental law, including the Berlin Rules on Water Resources (2004) and the UN General Assembly Resolution on the Human Right to Water and Sanitation (2010).

Ultimately, legality in international law includes both substance and process. While India's actions may be within the letter of the treaty, their political framing and aggressive posture may violate the spirit of cooperation required under both the IWT and customary water law. If India’s behaviour leads to the erosion of trust, refusal of data sharing, or procedural bypasses, it risks damaging a treaty that has long served as a buffer against broader hostilities.

Conclusion 

The Pahalgam attack presented a severe test for India’s national security and its diplomatic resolve. However, responding to terrorism through retaliatory shifts in water policy places the IWT on uncertain legal ground. While India is entitled to use its full share of water, politicising its use risks undermining a framework that has ensured regional water security for decades.

The treaty remains legally binding under international law, and its unilateral suspension or abrogation is not permitted under its text. India’s invocation of water as a retaliatory tool also challenges global norms against the militarisation or securitisation of essential environmental resources. Such actions could not only escalate conflict but also delegitimise India's position in future international water negotiations.

India must carefully balance its security imperatives with its treaty obligations. By demonstrating strict adherence to both the letter and spirit of the IWT – while using permitted mechanisms to resolve disputes and develop infrastructure – India can ensure long-term stability. The IWT should not become collateral damage in geopolitical rivalries; rather, it must remain a testament to peaceful cooperation in a volatile region.

(The writer is an attorney and lecturer of law at the Colombo University)

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The views and opinions expressed in this article are those of the author, and do not necessarily reflect those of this publication