Dhaka, May 6 -- India and Pakistan are stepping up both military and diplomatic efforts in response to a deadly attack in Indian-controlled Kashmir, raising concerns of potential conflict between the nuclear-armed neighbors.

India has accused Pakistan of supporting the militants responsible for the April 22 massacre that left 26 people dead, most of them Hindu tourists from India, labeling it a terrorist act. Pakistan has denied any involvement.

In retaliation, both nations have expelled each other's diplomats, closed their borders and airspace, and India has halted a key water-sharing agreement with Pakistan.

A Pakistani official recently claimed Islamabad has "credible intelligence" of a possible Indian strike, though no military act...