Early on the morning of Sept. 29, according to India’s Defense Ministry and military, Indian forces staged a “surgical strike” in Pakistan-administered Kashmir that targeted seven terrorist camps and killed multiple militants. Pakistan angrily denied that the daring raid took place, though it did state that two of its soldiers were killed in clashes with Indian troops along their disputed border. New Delhi’s announcement of its strike plunged already tense India-Pakistan relations into deep crisis. It came 11 days after militants identified by India as members of the Pakistani terrorist group Jaish-e-Mohammed killed 18 soldiers on a military base in the town of Uri, in India-administered Kashmir.

Amid all the shrill rhetoric and saber rattling emanating from India and Pakistan in recent days—including India’s home minister branding Pakistan a “terrorist state” and Pakistan’s defense minister threatening to wage nuclear war on India—one subtle threat issued by India may have sounded relatively innocuous to the casual listener.

In reality, it likely filled Pakistan with fear.

On Sept. 22, India’s Foreign Ministry spokesman suggested, cryptically, that New Delhi could revoke the Indus Waters Treaty (IWT). “For any such treaty to work,” warned Vikas Swarup, when asked if India would cancel the agreement, “it is important for mutual trust and cooperation. It cannot be a one-sided affair.”

The IWT is a 56-year-old accord that governs how India and Pakistan manage the vast Indus River Basin’s rivers and tributaries. After David Lilienthal, a former chairman of the Tennessee Valley Authority, visited the region in 1951, he was prompted to write an article in Collier’s magazine, in which he argued that a transboundary water accord between India and Pakistan would help ease some of the hostility from the partition—particularly because the rivers of the Indus Basin flow through Kashmir. His idea gained traction and also the support of the World Bank. The bank mediated several years of difficult bilateral negotiations before the parties concluded a deal in 1960. U.S. President Dwight Eisenhower described it as a “bright spot” in a “very depressing world picture.” The IWT has survived, with few challenges, to the present day.

And yet, it has now come under severe strain.

Ominously, Indian Prime Minister Narendra Modi told top officials present at the treaty review meeting that “blood and water cannot flow together.”

On Sept. 26, India’s government met to review the treaty but reportedly decided that it would not revoke the agreement—for now. New Delhi left open the possibility of revisiting the issue at a later date. Ominously, Indian Prime Minister Narendra Modi told top officials present at the treaty review meeting that “blood and water cannot flow together.” Additionally, the government suspended, with immediate effect, meetings between the Indus commissioners of both countries—high-level sessions that ordinarily take place twice a year to manage the IWT and to address any disagreements that may arise from it.

These developments have spooked Pakistan severely. Sartaj Aziz, the foreign affairs advisor to Pakistani Prime Minister Nawaz Sharif, said revoking the IWT could be perceived as an “act of war,” and he hinted that Pakistan might seek assistance from the United Nations or International Court of Justice.

If India were to annul the IWT, the consequences might well be humanitarian devastation in what is already one of the world’s most water-starved countries—an outcome far more harmful and far-reaching than the effects of limited war. Unlike other punitive steps that India could consider taking against its neighbor—including the strikes against Pakistani militants that India claimed to have carried out on Sept. 29—canceling the IWT could have direct, dramatic, and deleterious effects on ordinary Pakistanis.

The IWT is a very good deal for Pakistan. Although its provisions allocate three rivers each to Pakistan and India, Pakistan is given control of the Indus Basin’s three large western rivers—the Indus, Jhelum, and Chenab—which account for 80 percent of the water in the entire basin. Since water from the Indus Basin flows downstream from India to Pakistan, revoking the IWT would allow India to take control of and—if it created enough storage space through the construction of large dams—stop altogether the flow of those three rivers into Pakistan. To be sure, India would need several years to build the requisite dams, reservoirs, and other infrastructure to generate enough storage to prevent water from flowing downstream to Pakistan. But pulling out of the IWT is the first step in giving India carte blanche to start pursuing that objective.

Pakistan is deeply dependent on those three western rivers and particularly the Indus. In some areas of the country, including all of Sindh province, the Indus is the sole source of water for irrigation and human consumption. If Pakistan’s access to water from the Indus Basin were cut off or merely reduced, the implications for the country’s water security could be catastrophic. For this reason, using water as a weapon could inflict more damage on Pakistan than some forms of warfare.

If Pakistan’s access to water from the Indus Basin were cut off or merely reduced, the implications for the country’s water security could be catastrophic. 

To understand why, consider the extent of Pakistan’s water woes. According to recent figures from the International Monetary Fund, Pakistan is one of the most water-stressed countries in the world, with a per capita annual water availability of roughly 35,300 cubic feet—the scarcity threshold. This is all the more alarming given that Pakistan’s water intensity rate — a measure of cubic meters used per unit of GDP—is the world’s highest. (Pakistan’s largest economic sector, agriculture, consumes a whopping 90 percent of the country’s rapidly dwindling water resources.)

In other words, Pakistan’s economy is the most water-intensive in the world, and yet it has dangerously low levels of water to work with.

As if that’s not troubling enough, consider as well that Pakistan’s groundwater tables are plummeting precipitously. NASA satellite data released in 2015 revealed that the underwater aquifer in the Indus Basin is the second-most stressed in the world. Groundwater is what nations turn to when surface supplies are exhausted; it is the water source of last resort. And yet in Pakistan, it is increasingly imperiled.

There are other compelling reasons for India not to cancel the IWT, all of which go beyond the hardships the decision could bring to a country where at least 40 million people (of about 200 million) already lack access to safe drinking water.

First, revoking the treaty — an international accord mediated by the World Bank and widely regarded as a success story of transboundary water management — would generate intense international opposition. As water expert Ashok Swain has argued, revoking the IWT “will bring global condemnation, and the moral high ground, which India enjoys vis-à-vis Pakistan in the post-Uri period will be lost.” Also, the World Bank would likely throw its support behind any international legal action taken by Pakistan against India.

Second, if India decided to maximize pressure on Pakistan by cutting off or reducing river flows to its downstream neighbor, this would bottle up large volumes of water in northern India, a dangerous move that according to water experts could cause significant flooding in major cities in Kashmir and in Punjab state (for geographical reasons, India would not have the option of diverting water elsewhere). Given this risk, some analysts have proposed that New Delhi instead do something less drastic, and perfectly legal, to pressure Islamabad: build dams on the western rivers of the Indus Basin. The IWT permits this, even though these water bodies are allocated to Pakistan, so long as storage is kept to a minimum to allow water to keep flowing downstream. In fact, according to Indian media reports, this is an action Modi’s government is now actively considering taking.

Such moves, however, would not be cost-free for Pakistan. According to an estimate by the late John Briscoe, one of the foremost experts on South Asia water issues, if India were to erect several large hydroelectric dams on the western rivers, then Pakistan’s agriculture could conceivably lose up to a month’s worth of river flows—which could ruin an entire planting season. Still, it would not be nearly as serious as the catastrophes that could ensue if India pulls the plug on the IWT.

Third, if India ditches the IWT to punish its downstream neighbor, then it could set a dangerous precedent and give some ideas to Pakistan’s ally, China. Beijing has never signed on to any transboundary water management accord, and New Delhi constantly worries about its upstream rival building dozens of dams that cut off river flows into India. The Chinese, perhaps using as a pretext recent Indian defensive upgrades in the state of Arunachal Pradesh — which borders China and is claimed by Beijing — could well decide to take a page out of India’s book and slow the flow of the mighty Brahmaputra River. It’s a move that could have disastrous consequences for the impoverished yet agriculturally productive northeastern Indian state of Assam. The Brahmaputra flows southwest across large areas of Assam. Additionally, Beijing could retaliate by cutting off the flow of the Indus—which originates in Tibet—down to India, depriving New Delhi of the ability to limit the river’s flows to Pakistan.

Fourth, India’s exit from the IWT could provoke Lashkar-e-Taiba (LeT), the vicious Pakistani terrorist group that carried out the 2008 Mumbai attacks. LeT has long used India’s alleged water theft as a chief talking point in its anti-India propaganda, even with little evidence that New Delhi has intentionally prevented water from flowing downstream to Pakistan. If India backed out of the treaty and took steps to stop the flow of the Indus Basin’s western rivers, LeT would score a major propaganda victory and would have a ready-made pretext to carry out retaliatory attacks in India. An angry Pakistani security establishment, which has close links to LeT, would not go out of its way to dissuade the group from staging such attacks. Indeed, given the damaging effects India’s move could have on ordinary Pakistanis in such a water-insecure country, Pakistan would be keen to find ways to strike back at India.

What this all means is that India’s cancellation of the IWT would not produce New Delhi’s hoped-for result: Pakistani crackdowns on anti-India terrorists. On the contrary, Pakistan might tighten its embrace of such groups. The mere act of canceling the IWT — even if India declines to take steps to reduce water flows to Pakistan—would be treated in Islamabad as a major provocation, with fears that water cutoffs could follow, and thereby spawn retaliations.

To be sure, India has good reason to be unhappy about the IWT. The treaty allocates to India only 20 percent of the entire Indus River Basin’s water flows, and New Delhi knows it’s gotten the short end of the stick. Additionally, the IWT’s provisions limit India’s ability to build hydro-projects in Kashmir. These are significant matters in a nation with its own severe water stress. According to an estimate by the New Yorker, India boasts 20 percent of the world’s population but only 4 percent of its water. Not surprisingly, more than 300 million people in India face water shortages. Severe droughts have contributed to an alarming farmer suicide campaign that has claimed a staggering 300,000 lives over the last 20 years. And in an ominous indication of what the future may hold, India is consuming more groundwater than any other country in the world.

All this is to say that India has a strong case for requesting a renegotiation of the treaty. That would be a more prudent strategy than unilaterally revoking it.

India should preserve its decision to keep the IWT in place. Rescinding it could have disastrous consequences for Pakistan—and especially for ordinary Pakistanis—and also damaging results for India. With India-Pakistan relations nearly on a war footing, threatening a course of action that risks humanitarian devastation could bring the subcontinental powder keg one dangerous step closer to exploding.

This article originally appeared in Foreign Policy.

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