NEW DELHI — A deadly attack on tourists in Indian-controlled Kashmir has again moved India and Pakistan closer to war as the two rivals downgraded diplomatic and trade ties, closed the main border crossing and revoked visas for each other’s nationals.

Pakistan warned India on Thursday that it was committing an "act of war" by suspending a landmark water-sharing treaty in response to a deadly terror attack in Indian-controlled Kashmir. The threat from Pakistan Prime Minister's Office followed a number of diplomatic measures imposed by New Dehli on Islamabad as tensions flare between the neighboring nuclear powers.

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.