The last time India and Pakistan faced off in a military confrontation, in 2019, U.S. officials detected enough movement in the nuclear arsenals of both nations to be alarmed. Secretary of State Mike Pompeo was awakened in the middle of the night. He worked the phone “to convince each side that the other was not preparing for nuclear war,” he wrote in his memoir.

That clash quickly cooled after initial skirmishing. But six years later, the two South Asian rivals are again engaged in military conflict after a deadly terrorist attack against tourists in Indian-controlled Kashmir. And this time there is a new element of uncertainty as the region’s most important military alliances have been redrawn.

Changing patterns in the flow of arms illustrate the new alignments in this particularly volatile corner of Asia, where three nuclear powers — India, Pakistan and China — stand in uneasy proximity.

India, a traditionally nonaligned country that has shed its history of hesitance toward the United States, has been buying billions of dollars in equipment from the United States and other Western suppliers. At the same time, India has sharply reduced purchases of low-cost arms from Russia, its Cold War-era ally.

Pakistan, whose relevance to the United States has waned since the end of the war in Afghanistan, is no longer buying the American equipment that the United States once encouraged it to acquire. Pakistan has instead turned to China for the vast majority of its military purchases.