As a first step, one American official said, Pakistan would have to stop pursuing tactical nuclear weapons, which are more likely to be used in a conflict with India and could more easily fall into the hands of terrorists, and halt development of long-range missiles. Pakistan should also sign the treaty banning nuclear weapons tests.

Such moves would undoubtedly be in Pakistan’s long-term interest. It cannot provide adequate services for its citizens because it spends about 25 percent of its budget on defense. Pakistan’s army, whose chief of staff is due to visit Washington this month, says it needs still more nuclear weapons to counter India’s conventional arsenal.

The competition with India, which is adding to its own nuclear arsenal, is a losing game, and countries like China, a Pakistan ally, should be pushing Pakistan to accept that. Meanwhile, Narendra Modi, India’s prime minister, has done nothing to engage Islamabad on security issues, and he also bears responsibility for current tensions. The nuclear arms race in South Asia, which is growing more intense, demands far greater international attention.