In tit-for-tat moves this week, India and Pakistan have entered a strategic standoff following Tuesday’s attack on tourists in Indian-administered Kashmir, which resulted in the deaths of at least 26 people.

On Wednesday, India downgraded ties with Pakistan, announcing a series of steps, the most important of which is a decision to suspend its participation in the Indus Waters Treaty (IWT), which could seriously restrict Pakistan’s water supplies.

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India has also closed its main land border with Pakistan and given some Pakistani nationals currently in India a deadline to leave the country.

On Thursday, Pakistan retaliated with similar steps against India, and also threatened to suspend its participation in all bilateral agreements between the two, including the 1972 Simla Agreement, a peace accord drawn up following their war the previous year that led to the creation of Bangladesh.

Pakistan is particularly angered by the threat to the IWT and has warned India that any disruption to its water supply would be considered “an act of war”, adding that it was prepared to respond, “with full force across the complete spectrum of national power”.

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The IWT, a transboundary water agreement that allows the two countries to share water flowing from the Indus basin, has survived armed conflicts and near-constant tensions between India and Pakistan over the past 65 years. While India came close to suspending the treaty in 2019, it did not go through with it.

Why has India taken action against Pakistan?

An armed group called The Resistance Front (TRF), which demands independence for Kashmir, has claimed responsibility for Tuesday’s attack in Pahalgam, one of Indian-administered Kashmir’s most popular tourist destinations. Indian authorities have previously claimed that TRF is an offshoot of the Lashkar-e-Taiba, an armed group based in Pakistan.

India has long held that Pakistan backs the armed rebellion in Kashmir, a charge Islamabad denies. On Wednesday, India claimed that the Pahalgam attack had “cross-border” linkages, blaming its western neighbour.

During a special briefing by the Indian Ministry of External Affairs on Wednesday, Foreign Secretary Vikram Misri said that the Cabinet Committee on Security (CCS) had been called to discuss the attack in which men armed with rifles killed 25 Indian tourists and one Nepalese tourist, all men.

“In the briefing to the CCS, the cross-border linkages of the terrorist attack were brought out,” Misri said.

Misri added: “The Indus Waters Treaty of 1960 will be held in abeyance with immediate effect until Pakistan credibly and irrevocably abjures its support for cross-border terrorism.” For a treaty to be in abeyance means that it is temporarily suspended or on hold.

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Earlier on Thursday, India’s Prime Minister Narendra Modi said that India would identify, track and punish every “terrorist” and their backers.

What is the Indus Waters Treaty?

Signed in 1960, the origins of the IWT trace back to August 1947, when British colonial rule over the Indian subcontinent ended and India and Pakistan became two separate sovereign states. India is the upper riparian (located upstream) while Pakistan is the lower riparian, which means India has control over how the river flows.

Because both countries rely on the water from the Indus basin’s six rivers for irrigation and agriculture, they signed an agreement called the Standstill Agreement to continue allowing the flow of water across the border. When the Standstill Agreement expired in 1948, India stopped the water flow towards Pakistan from its canals, prompting an urgent need for negotiations on water sharing.

Following nine years of negotiations mediated by the World Bank, former Pakistani President Ayub Khan and former Indian PM Jawaharlal Nehru signed the IWT [PDF] in September 1960. The treaty gives India access to the waters of the three eastern rivers: the Ravi, Beas and Sutlej.

Pakistan, in turn, gets the waters of the three western rivers: the Indus, Jhelum and Chenab.

India can use the western rivers to generate hydroelectric power and for some limited agriculture, but cannot build infrastructure that restricts the flow of water from those rivers into Pakistan or redirects that water.

What would the suspension of this treaty mean for Pakistan?

It represents a threat from India that it could, if and when it chooses to, restrict the flow of water from the Indus, Jhelum and Chenab into Pakistan.

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It does not mean that India plans to limit that flow immediately.

Even if it wanted to, it is unlikely that India could immediately stop the flow of water even though it has suspended its participation from the treaty.

This is because India has upstream reservoirs constructed on the western rivers, but their storage capacity cannot hold enough volumes of water to hold back water entirely from Pakistan. It is also high-flow season when ice from glaciers melts between May and September, keeping water levels high.

“The western rivers allocated to Pakistan carry very high flows, especially between May and September. India does not currently have the infrastructure in place to store or divert those flows at scale,” Hassaan F Khan, assistant professor of urban and environmental policy and environmental studies at Tufts University in the United States, told Al Jazeera.

However, if India were to try to stop – or cut – the water flow, Pakistan might feel the effects in seasons when water levels are lower. Pakistan relies heavily on the water from the western rivers for its agriculture and energy. Pakistan does not have alternative sources of water.

Pakistan has a largely agrarian economy, with agriculture contributing 24 percent to the country’s gross domestic product (GDP) and 37.4 percent to employment, according to Pakistan’s most recent economic survey published in 2024. The country’s statistics bureau says that the majority of the population is directly or indirectly dependent on the agriculture sector. According to the World Bank, the country’s current population is about 247.5 million.

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Does India have the power to suspend this treaty?

While India has declared abeyance from the treaty, legal experts say that it cannot unilaterally suspend the treaty.

“India has used the word abeyance and there is no such provision to ‘hold it in abeyance’ in the treaty,” Ahmer Bilal Soofi, a Pakistani lawyer, told Al Jazeera. The treaty can only be modified by mutual agreement between the parties.

“It also violates customary international laws relating to upper and lower riparian where the upper riparian cannot stop the water promise for lower riparian,” Soofi said.

Anuttama Banerji, a political analyst based in New Delhi, told Al Jazeera that the treaty might continue, but not in its present form. “Instead, it will be up for ‘revision’, ‘review’ and ‘modification’ – all three meaning different things – considering newer challenges such as groundwater depletion and climate change were not catered for in the original treaty,” Banerji said.

“In principle, a unilateral suspension of a bilateral treaty can be challenged as a breach of international law,” Khan, the Tufts University assistant professor, told Al Jazeera.

However, the enforcement of this is complicated, Khan added. “The Indus Waters Treaty is a bilateral agreement without a designated enforcement body. While the World Bank has a role in appointing neutral experts and arbitrators, it is not an enforcement authority.”

Khan explained that if Pakistan wanted to pursue legal recourse, it would likely be through international forums such as the International Court of Justice (ICJ). “In practice, the main costs for India would be reputational and strategic: undermining its image as a rules-based actor, especially given its own status as a downstream riparian on other transboundary rivers.”

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Khan said that the broader strategic goal of the IWT suspension seems to be a renegotiation of the treaty. “India has been signalling its desire to revise or renegotiate the treaty for some time,” he said, explaining that India had asked to renegotiate the treaty in January 2023 and again in September 2024, citing climate change and implementation challenges. Pakistan has so far refused.

“The recent announcement appears to be an attempt to apply pressure and force a renegotiation on terms more favourable to India. Whether this strategy succeeds remains to be seen, but it marks a significant departure from six decades of treaty stability.”

What other steps is India taking in response to the attack in Kashmir?

Besides the abeyance of the IWT, Mirsi announced other steps, including:

• The main land border crossing between the two countries, the Integrated Check Post Attari, or the Attari-Wagah crossing, will be closed with immediate effect and those who have crossed over with “valid endorsements” have to return through the route before May 1.
• Any SAARC Visa Exemption Scheme (SVES) visas granted to Pakistanis have been cancelled and any Pakistani currently visiting India on the SVES visa has to leave within 48 hours of the statement issued on Wednesday.
• The military, naval and air advisers in the Pakistani High Commission in New Delhi are considered personae non gratae and have a week to leave India, while Indian military, naval and air advisers will be pulled back from the Indian High Commission in Islamabad. To be persona non grata in a country means to be unwelcome.
• Five support staff members will also be pulled from each High Commission.
• The staffing for each High Commission will be reduced from 55 members to 30 through further reductions by May 1.

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How has Pakistan responded to India’s measures?

On Thursday, Pakistan’s Prime Minister Shehbaz Sharif called a high-level meeting of the National Security Committee (NSC).

A statement released by Sharif’s office on Thursday said: “the Committee reviewed the Indian measures announced on 23 April 2025 and termed them unilateral, unjust, politically motivated, extremely irresponsible and devoid of legal merit”.

The statement adds: “Pakistan vehemently rejects the Indian announcement to hold the Indus Waters Treaty in abeyance … Any attempt to stop or divert the flow of water belonging to Pakistan as per the Indus Waters Treaty … will be considered as an Act of War and responded with full force.

“Pakistan shall exercise the right to hold all bilateral agreements with India, including but not limited to Simla Agreement in abeyance, till India desists from its manifested behaviour of fomenting terrorism inside Pakistan; trans-national killings; and non-adherence to international law and UN Resolutions on Kashmir.”

The Simla Agreement was a peace treaty signed between Pakistan and India in 1972, which emphasised resolving conflict between the two countries peacefully and through bilateral negotiations.

On the same day, Pakistan also announced the closure of the Wagah border, suspended all visas under the SAARC Visa Exemption Scheme (SVES) issued to Indian nationals and declared Indian army and navy advisers in Islamabad personae non gratae.

Pakistan has also closed its airspace “with immediate effect” for all Indian owned or Indian operated airlines. It has also suspended all trade with India “including to and from any third country through Pakistan” – in effect saying that it won’t allow India to export to Afghanistan through its territory.

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In the past, Pakistani officials have warned that India’s interference in water flow to Pakistan would be deemed an act of war, prompting retaliation.

In 2016, the then-chairman of Pakistan’s Senate, Raza Rabbani, said: “Interference with Pakistan’s water supply will be tantamount to an act of aggression and aggression will be met by aggression.”

Does this spell a major escalation in tensions between the two countries?

The suspension of the IWT is significant. While India has threatened to suspend it before, it has never actually gone through with its threat.

In 2016, suspected rebel fighters killed 17 Indian soldiers in the Uri area in Indian-administered Kashmir. Four suspected rebels were also killed by the Indian army during this attack. In the aftermath of the Uri attack, Modi said: “blood and water can’t flow together” when discussing the IWT with government officials. However, the IWT was not suspended after this.

In 2019, a suicide bomber killed 40 paramilitary police in Indian-administered Kashmir’s Pulwama. This attack was claimed by Jaish-e-Muhammad, an armed group based in Pakistan. In the aftermath, Indian Water Resources Minister Nitin Gadkari threatened to suspend the flow of water to Pakistan. However, this threat did not materialise.

Hence, India’s recent suspension of the treaty is the biggest escalation of its kind in the hydropolitics of the Indus basin.