India said it would immediately suspend the Indus Waters Treaty with Pakistan as part of measures to downgrade diplomatic ties with its neighbour after militants attacked tourists in Kashmir, killing 26 men.
The treaty had survived two wars between the bitter rivals and withstood many twists and turns in diplomatic ties before New Delhi's decision on Wednesday.
WHAT IS THE INDUS WATERS TREATY?
The nuclear-armed neighbours disagree over use of the water from rivers that flow downstream from India into the Indus river basin in Pakistan.
The use of the water is governed by the Indus Waters Treaty, which was mediated by the World Bank and signed by the neighbours in September 1960.
The agreement split the Indus and its tributaries between the two countries and regulated water sharing. India was granted the use of water from three eastern rivers - Sutlej, Beas and Ravi - while Pakistan was granted most of the three western rivers - Indus, Jhelum and Chenab.
There is no provision in the treaty for either country to unilaterally suspend or terminate the pact, which has clear dispute resolution systems.
WHAT ARE THE CONCERNS OVER WATER?
The nuclear-armed neighbours have argued over and disputed several projects on the Indus and its tributaries in India for years.
Pakistan is heavily dependent on water from this river system for its hydropower and irrigation needs. Pakistan says India unfairly diverts water with the upstream construction of barrages and dams, a charge India denies.
Pakistan is concerned that India's dams will cut flows on the river, which feeds 80% of its irrigated agriculture. It has asked for a neutral expert and then an arbitration court to intervene in two recent hydropower projects.
India has accused Pakistan of dragging out the complaints process, and says the construction of its Kishanganga and Ratle hydroelectric projects is allowed under the treaty. It has also sought modification of the pact to get around such delays.
WHAT COULD THE SUSPENSION CHANGE?
The suspension of the accord is not expected to have an immediate impact on the flow of water to Pakistan as India does not have enough storage capacity.
But India's move could bring uncertainty for Pakistan's agricultural system.
The suspension means India can stop sharing crucial information and data on release of water from barrages/dams or on flooding, Indian officials said, adding that New Delhi will also not be obliged to release minimum amounts of water during the lean season.
HOW HAS PAKISTAN REACTED TO THE DECISION?
The treaty is a binding international agreement brokered by the World Bank and contains no provision for unilateral suspension, a statement from Pakistan Prime Minister Shehbaz Sharif's office said on Thursday.
"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 as an Act of War and responded with full force," the statement said.
Pakistan's status as "lower riparian" refers to its downstream position.
Ghasharib Shaokat, the head of product at Pakistan Agriculture Research, called the treaty the backbone of the country's agriculture sector.
"It puts our agricultural future on shaky ground. If water flows become erratic, the entire system takes a hit — especially irrigation-dependent crops such as wheat, rice, and sugarcane," Shaokat said.
"Yields could drop. Costs could rise. Food prices would likely spike. And small-scale farmers, who already operate on thin margins, would bear the brunt of it."
Khalid Hussain Baath, chairman of a national farmers' union in Pakistan, painted the move as an act of belligerence.
"This is a true war," Baath said from Lahore. "We already have a water shortage because of climate change. Low rainfall this year, and limited snow means that the water level is already 20-25% lower than last year."
