India has taken the first tangible step in violation of the Indus Waters Treaty (IWT) in 1960, when authorities began working to increase reservoir’s holding capacity of two hydropower projects in the Indian illegally occupied Jammu and Kashmir (IIOJK), sources have told Reuters.

A “reservoir chicken” process for the removal of sediment began on Thursday, performed by India’s largest hydroelectric company, the state NHPC LTD, and the relevant authorities, the three sources said, adding that the work may not immediately threaten the supply to Pakistan, but it could in the long run.

India suspended IWT – which secures supply to 80% of the Pakistani farms – after the killing of 26 people in IIOJK’s tourist town of Pahaldam last month. Without giving any evidence, India accused Pakistan of the attack and triggered increased tensions between the two countries.

Pakistan, who refused any role in the Pahagam attack, has threatened international trial of the suspension of IWT and warned, “Any attempt to stop or divert the flow of water belonging to Pakistan … will be considered an act of war.”

According to the sources, India did not inform Pakistan about the work on the Salal and Baglihar projects, which were performed for the first time since the projects were built in 1987 and 2008-09 respectively, when IWT had blocked such work, the sources say.

The reservoir rinse process initially results in the release of sediment -loaded waters downstream from the reservoirs, which potentially causes sudden flooding, followed by a reduced water flow when the reservoirs are replenished, one of the sources said.

They said the work may not immediately threaten the supply to Pakistan, but it could eventually be affected if other dams launch similar efforts. There are more than half a dozen such projects in the occupied region.

The flush surgery ran for three days from May 1, one of the sources of Reuters told. “We were also asked to open the adjustable gates for cleaning, which we did from May 1,” the source said, adding that the effort aimed at freeing up dam surgeries from any restrictions.

“This is the first time such an exercise has taken place and will help with more effective power production and prevent damage to turbines,” the source said. The locals who lived on the shores of the Chenab River also confirmed that water had been released from both Salal and Baglihar damings from Thursday to Saturday.

Rinse of hydropower projects requires almost to empty a reservoir to force the sediment, whose structure is a major cause of falling output. “Flushing is not a common thing because it leads to a lot of waste of water,” said one of the sources.

Two of the sources said that power supplied by the 690-Megawatt Salal project was far below its capacity because Pakistan had prevented such rinsing, while silt building also affected output on the 900-MW Baglihar project.

“Downstream countries were expected to be informed if it led to any flood,” said the source, as under IWT, India had to share data such as hydrological currents in various places on the rivers flowing through India and emitting flood warnings.

Government officials and experts on both sides say that India cannot stop water flow immediately, but since IWT has allowed it to build only so-called run-of-river developments that do not require significant storage dams on the three rivers assigned to Pakistan.

The IWT suspension means that India “can now pursue our projects at Free Will,” said Kus Whant Vohra, a recently retired leader of India’s central water commission, which worked a lot on Indus advanced with Pakistan.