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.

The nuclear-armed rivals, which both claim Kashmir and administer separate parts of it, are at a dangerous crossroad after Tuesday’s militant attack, analysts said.

India announced a series of retaliatory actions, and hinted at the possibility of more, in response to what it called Pakistan’s support of terrorism on Indian soil.