On the eve of President Obama's visit to India, U.S. National Security Council spokesman Mike Hammer responded to a question from a Pakistani journalist by playing down the significance of the trip for relations with Pakistan. The United States enjoys “very positive and fruitful relations with both countries, with both India and Pakistan” he said, “and one is not at the expense of the other." But the biggest challenge for the United States or any other outside power in fashioning policy toward South Asia is that both India and Pakistan very much see anything that benefits one as being at the expense of the other.

This obdurately zero-sum attitude makes it easy for even the most innocent and well-intentioned action by an outsider to give offense to one or the other of the South Asian contenders, and sometimes even to both at the same time. Following 9/11, India looked forward to counterterrorism as a vehicle for enhanced cooperation with the United States, with New Delhi noting that it had been engaged in fighting terrorists for quite some time. When the U.S. focus on Afghanistan led it, for obvious geographic reasons, to do more counterterrorist business with Pakistan, the Indians viewed this with dismay, seeing Pakistan more as part of the problem than as part of the solution when it comes to terrorism.

U.S. policymakers have recognized the difficulty and delicacy that this South Asian competition presents them. They have tried to deal with it by repeatedly disavowing any taking of sides and by side-stepping issues that are most likely to get the Indian and Pakistani competitive juices flowing. Just as understandably, they have recognized that India is the weightier of the two South Asian powers and the one more useful to such global objectives as offsetting China. For that and other reasons—such as India being the more reliably democratic of the two states—a tilt toward India over the past two decades has been an appropriate correction to the Cold War anomaly of India having had better relations with the Soviet Union and Pakistan better relations with the United States. So Washington now tries in particular to avoid saying or doing anything having to do with the South Asian competition that would anger New Delhi.

That posture means not poking into the most contentious and bitter of the issues that divide India and Pakistan: the status of Kashmir. Pakistan seeks international involvement in the dispute; India, as the status quo power, strongly opposes such involvement. Obama, when still a candidate, disturbed the Indians when he talked about appointing an envoy to mediate a Kashmir settlement. Since then, the administration has been careful to maintain the public position that, as Hammer put it in this week's press briefing, the dispute is one for India and Pakistan to resolve directly. When Richard Holbrooke was appointed a special envoy for South Asia, his charter was clearly defined not to include India or by implication anything having to do with Kashmir.

This posture is understandable and tactically makes sense. But it in effect acquiesces in the indefinite festering of a conflict that, more than any other issue, sets the tone of Indian-Pakistani relations and thereby exacerbates the difficulties of diplomacy in a zero-sum climate. The dispute also directly sustains other dangers and problems important to U.S. interests. It carries the risk of touching off, as it has in the past, another Indo-Pakistani war, this time between two powers with nuclear weapons. It also is intertwined with problems of terrorism and extremism in Pakistan and Afghanistan. When U.S. cruise missiles struck a camp in Afghanistan in 1998 in retaliation for Al Qaeda's bombing of U.S. embassies in Africa, the single biggest group of militants killed at the camp were Kashmiris.

Despite the absence of a Kashmiri peace process, the lines of a potential settlement have been fairly clear for some time. An agreement would make the current line of control—an armistice line left from previous rounds of warfare—an international boundary. The more populous, Indian-controlled part of Kashmir would unmistakably remain part of India, but with enough state-level control of affairs to make a settlement stable and palatable to Muslims. During the last part of his rule in Pakistan, Pervez Musharraf seemed to have decided that some such arrangement was acceptable. But any chance to explore the possibilities through a budding Indian-Pakistani rapprochement was cut short by the terrorist attack in Mumbai in 2008.

The current presidential visit probably is not the time to try to move on this issue. But any future opportunities to do so should be seized.