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.

Tensions between India and Pakistan are escalating following a terror attack in the India-administered Kashmir region that killed 26 tourists, with each country suspending key treaties and cutting diplomatic ties.

The Pakistani government said that if India followed through on a threat to block rivers it would take it as “an act of war.”