New Delhi has said it is going to suspend the Indus Waters Treaty – a 1960 river-sharing agreement with Pakistan brokered by the World Bank – in response to the recent killing of 26 tourists in the mountain town of Pahalgam in India-administered Kashmir.

India has held Pakistan indirectly responsible for the worst attack in years in the disputed region that both countries claim in full but administer in part.

While rejecting the Indian decision to hold the Indus Water Treaty in abeyance, Pakistan said the agreement is “binding” and contains no provision for unilateral suspension.

“Any attempt to stop or divert the flow of water belonging to Pakistan as per the Indus Waters Treaty and the usurpation of the rights of lower riparian will be considered an act of war and responded with full force across the complete spectrum of national power,” it said.

One of the reasons the treaty has withstood three wars, terror incidents and frequent border fights over the last 65 years is that it is in the mutual interest of both water-stressed countries to avoid conflict.

“India can’t unilaterally stop Pakistan’s water supply for three reasons: geography, engineering, and international law,” Abid Qaiyum Suleri, executive director of Islamabad-based think tank Sustainable Development Policy Institute, tells TRT World.

The treaty allows neither Pakistan nor India to unilaterally terminate or suspend the agreement, which includes mechanisms to address disputes.

“Brokered by the World Bank, the treaty legally divides river usage. Violating it would invite global condemnation and ruin both countries,” he says.

Lifeline for both nations

The Indus River system originates in the Himalayas and includes the main Indus River as well as its five major tributaries, namely Jhelum, Chenab, Ravi, Beas, and Sutlej.

As such, the system provides the two countries with a critical lifeline for agriculture, hydropower, and domestic water needs. The river headwaters are in India-administered Kashmir.

This geographical asymmetry led to immediate tensions over water rights after the partition of the Subcontinent into India and Pakistan in 1947.

Mediated by the World Bank, negotiations for a water distribution agreement began in the early 1950s and concluded in 1960 in the form of the Indus Waters Treaty.

The treaty divides the six rivers into two groups. The three eastern rivers -- Ravi, Beas, and Sutlej -- went to India for mostly unrestricted use.

The three western rivers -- Indus, Jhelum, and Chenab -- were allocated to Pakistan, even though India received the right to use their waters in limited quantities for non-consumptive purposes like hydropower generation.

In the immediate run, India cannot stop Pakistan’s water even if it sets its mind to it. Glaciers melt between May and September every year, resulting in massive water flows that can’t be stored or diverted away, at least in the short term.

“The Indus River system is governed by gravity and topography, not politics. Diverting it would defy the Himalayan gradient and cause massive tectonic disruptions in a region, which lies in many seismic fault-lines,” says Suleri.

Moreover, India’s reservoirs on the western rivers are run-of-the-river dams that generate electricity without much storage, he says.

The total live storage of Kishanganga and Baglihar dams, which India has built on western rivers belonging to Pakistan, is only a fraction of Pakistan’s annual water requirement, he adds.

“While water warfare sounds dramatic, it’s a bluff. Nature, physics, and the treaty prevent New Delhi from shutting down Pakistan’s rivers,” Suleri says.

What if there’s a disagreement?

The absence of a provision explicitly allowing either party to unilaterally suspend the agreement suggests that the treaty is binding indefinitely. This is perhaps the reason it has endured the periods of heightened tensions, like the wars of 1965, 1971, and 1999.

As for dispute resolution, the treaty provides a three-tiered mechanism. The first mediation platform is the Permanent Indus Commission (PIC), which consists of one commissioner from each country to oversee the treaty’s implementation and ensure a timely exchange of water data.

When the PIC cannot resolve a dispute, it is referred to a “neutral expert” appointed by the World Bank.

For disputes of more serious nature, the treaty allows that a seven-member court of arbitration be set up. The World Bank then plays a facilitative role in appointing arbitrators but is not a party to the dispute resolution process.

What about ‘material breach’?

The Indus Water Treaty is governed by the Vienna Convention on the Law of Treaties (1969), which both India and Pakistan have ratified.

Under the Vienna Convention, a treaty can be terminated or suspended only by mutual consent, through a new agreement, or under specific circumstances, such as “material breach”.

For example, India could make a case for the treaty’s suspension if Pakistan failed to share data. However, proving a material breach requires adjudication, a formal process that requires the involvement of all parties.

Not a smooth ride

Pakistan has frequently raised objections to India’s run-of-the-river hydropower projects on the western rivers, arguing that they violate the treaty by altering water flows.

Pakistan objected to India’s construction of the Salal Hydropower Project in the 1970s on Pakistan’s Chenab River. The dispute was resolved bilaterally through design modifications.

In the 2000s, India built Baglihar Dam on the same Pakistani river. Islamabad then raised objections and referred it to a neutral expert, who ruled in India’s favour with minor adjustments in the reservoir’s structure.

Pakistan has referred Kishanganga and Ratle projects to a neutral expert and a court of arbitration where proceedings are currently ongoing.

A tool for arm-twisting?

India has periodically hinted at using the treaty for political leverage, particularly after terror attacks that it blamed on Pakistan.

After the 2016 Uri terror attack, Indian Prime Minister Narendra Modi said: “Blood and water cannot flow together”. In response, Pakistan accused India of committing water terrorism.

In 2023, India sought modifications to the treaty, citing Pakistani obstruction. When Pakistan refused to renegotiate the treaty, India sought the intervention of a neutral expert while Pakistan went to the court of arbitration. The dispute is ongoing.

Seasoned Pakistani diplomat Maleeha Lodhi says India had made it clear two years ago that it wanted to “get out of this treaty”.

“Then in August last year, India formally communicated to Pakistan that it wanted a review because of changes in the situation… but these were excuses for India to somehow wriggle out of the treaty,” she says.