India has for the first time issued a notice to Pakistan, seeking a review and modification of the Indus Waters Treaty (IWT), in view of Islamabad's "intransigence" to comply with the dispute redressal mechanism of the pact that was signed more than six decades ago for matters relating to cross-border rivers, government sources said on Friday.

The notice, sent by India's Indus water commissioner to his Pakistani counterpart on January 25 under the provisions of the pact, seeks Islamabad's response within 90 days for inter-governmental negotiations to "rectify the material breach" of the IWT.

Government sources said India's call for the review and modification of the pact is not specific to the dispute resolution mechanism only, and that the negotiations could cover various other provisions of the pact, based on the experiences gained over the last 62 years.

India took the significant step around 10 months after the World Bank announced appointing a neutral expert and a chair of the Court of Arbitration under two separate processes to resolve the differences over the Kishenganga and Ratle Hydro Electric Projects, following Islamabad's refusal to address the matter through talks between the two commissioners.

The sources said according to India, the start of the two concurrent processes to resolve the dispute violates the provision of the three-step graded mechanism prescribed in the pact and wondered what will happen if the mechanisms come out with contradictory judgements.

India and Pakistan signed the IWT on September 19, 1960 after nine years of negotiations, with the World Bank being a signatory to the pact that sets out a mechanism for cooperation and information exchange between the two sides on the use of the waters of a number of cross-border rivers.

"The objective of the notice for modification is to provide Pakistan with an opportunity to enter into intergovernmental negotiations within 90 days to rectify the material breach of the IWT. This process would also update the IWT to incorporate the lessons learned over the last 62 years," a source said.

The sources said the immediate trigger to send the notice was Pakistan's "intransigence" for a solution to the differences over the Kishenganga and Ratle Hydro Electric Projects in accordance with the provisions of the IWT.

Under the pact, any difference needs to be resolved under a three-stage approach. However, in case of the Kishenganga and Ratle Hydro Electric Projects, the World Bank started two concurrent dispute redressal processes at the insistence of Pakistan, which India felt was a breach of the IWT.

Commenting on the Indian move, spokesperson in the Pakistani foreign office Mumtaz Zahra Baloch said: "As we speak, a court of arbitration is holding its first hearing in The Hague on Pakistan's objections to the Kishanganga and Ratle Hydro Electric projects." "The court of arbitration has been set up under the relevant provisions of the Indus Waters Treaty. Such...reports should not divert attention from the important proceedings of the court of arbitration," she added.

The government sources said New Delhi has always been a steadfast supporter and a responsible partner in the implementation of the IWT in its letter and spirit.

"However, Pakistan's actions have adversely impinged on the provisions of the IWT and their implementation, and forced India to issue an appropriate notice for a modification of the pact," a source said.

In 2015, Pakistan requested for the appointment of a neutral expert to examine its technical objections to India's Kishenganga and Ratle Hydro Electric projects (HEPs).

In 2016, Pakistan unilaterally retracted the request and proposed that a court of arbitration adjudicate on its objections, the sources said.

The sources said this "unilateral action" by Pakistan was in contravention of the graded mechanism of dispute settlement envisaged by Article IX of the IWT.

Accordingly, India made a separate request for the matter to be referred to a neutral expert.

"The initiation of two simultaneous processes on the same questions and the potential of their inconsistent or contradictory outcomes create an unprecedented and legally untenable situation, which risks endangering the IWT itself," a source said.

"The World Bank acknowledged this in 2016 and took a decision to pause the initiation of two parallel processes and request India and Pakistan to seek an amicable way out," the source added.

The sources said despite repeated efforts by India to find a mutually agreeable way forward, Pakistan refused to discuss the issue during the five meetings of the Permanent Indus Commission from 2017 to 2022.

At Pakistan's continuing insistence, the World Bank last year initiated actions on both the neutral expert and court of arbitration processes, they said, adding that such parallel consideration of the same issues is not covered under any provision of the IWT.

"Faced with such a violation of IWT provisions, India has been compelled to issue the notice of modification," one of the sources said.

Under the provisions of the IWT, in case of any questions on any project or initiative, the Indus commissioners attempt to resolve those under the first step. If they fail, then the questions become "differences" and the World Bank has to appoint "neutral experts".

If the "neutral experts" fail to find a resolution, the differences become disputes and, in such a scenario, the World Bank has to appoint a court of arbitration to find a way out, the sources said.

In the case of the Kishenganga and Ratle Hydro Electric Projects, Pakistan asked for the appointment of neutral experts in 2015. Subsequently, it demanded the appointment of the court of arbitration in 2016, skipping the second stage of the dispute redressal, they said.

In 2016, the World Bank followed the processes of finding a resolution by the neutral experts as well as the CoA following Pakistan's insistence. India, at that point, wondered what would happen if the two mechanisms came out with contradictory outcomes, the sources said.

Following India's objections, the World Bank put a pause on both the processes and asked the two sides to resolve the matter at the meetings of the Indus commission. The pause was withdrawn in March last year, they said.

In March last year, the World Bank announced starting the two concurrent processes and subsequently, appointed a neutral expert and a chair of the CoA.

When the two concurrent processes resumed in March last year, India only cooperated with the neutral expert and has been skipping the process being followed by the CoA.

"Now we have reached a stage that if we allow both the processes to move forward, it may result in contradictory judgements and will put a question mark over the integrity of the treaty itself. That is the immediate and legal reason for the modification of the treaty," a source said.

The sources said India has learnt many lessons over the last 62 years and it feels it is time to make the treaty "more up to date".

There is a provision in the treaty for modification and there could be many things that India may like to change or Pakistan may like to change.

Under the IWT, all the waters of the eastern rivers -- Sutlej, Beas and Ravi -- amounting to around 33 million acre feet (MAF) annually, is allocated to India for unrestricted use.

The waters of the western rivers -- Indus, Jhelum and Chenab -- amounting to around 135 MAF annually, have been assigned largely to Pakistan. India is permitted to construct the run of the river plants on the western rivers with a limited storage, according to the criteria specified in the treaty.

According to the provisions of Article VIII(5) of the IWT, the Permanent Indus Commission is required to meet at least once a year.

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