On 10 January 1966, then Indian Prime Minister Lal Bahadur Shastri and Pakistan President Ayub Khan signed a pact in Tashkent with Soviet Premier Alexei Kosygin as the mediator to resolve the terms of peace after the Indo-Pakistani War of 1965. On the next day, Shastri died suddenly, reportedly due to a heart attack. It is widely speculated that Shastri was killed by poisoning the water he drank.