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.

After a militant attack in Kashmir, the Indian government said it was suspending its participation in a treaty that governs most of the water used in Pakistani agriculture.

Relations between India and Pakistan are cratering following a deadly militant attack in Indian-administered Kashmir that has sparked tit-for-tat reprisals and raised fears of another military escalation between the nuclear-armed rivals.