The risk of exposing a military still being modernized may constrain Prime Minister Narendra Modi as he weighs retaliation for a terrorist attack.

A day after India suspended a water-sharing treaty and downgraded diplomatic ties with Pakistan, authorities in Islamabad closed airspace to Indian aircraft and suspended all trade with India.

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.