A flare-up in a long-running border dispute between China and India has raised the temperature in their bilateral relationship. Yet it may be just as significant for the trilateral U.S.-China-India relationship, which will do a great deal to shape the strategic landscape of the 21st century.

As the U.S.-China rivalry goes global, India may be the only nonaligned country that can, by itself, make a major difference in the balance of influence and advantage. The good news is that the geopolitics of the triangle are producing a tighter U.S.-India partnership. The bad news is that trade frictions and India’s internal politics are getting in the way.

The details of the border crisis are murky, in part because both governments are remaining tight-lipped. But it’s clear that China and India are in the midst of one of their most serious showdowns in decades, 4,270 meters above sea level in the Himalayas. There are reports of several Chinese incursions into Indian-held land, including territory beyond what Beijing has traditionally claimed. China has sent thousands of troops to reinforce its presence in the area; both sides are reportedly deploying heavy weapons to bases near the area in dispute.