There is near-universal dismay at the drift in the U.S.-India partnership, with most observers viewing it as a strategic blunder by Washington.

A decade from now, there is likely to be heated debate in the United States over “who lost India,” an accounting that may rival the “who lost China?” conflagration for its capacity to settle scores and disrupt or destroy lives.

Displaying a diplomatic adroitness not often in evidence, China has been quick to exploit the opportunity, promoting a renewed relationship with its neighbor despite clashes between the two countries’ armed forces that left scores of casualties. The pace of India-China rapprochement is set to slow and has limits, but U.S. actions have confirmed suspicions in New Delhi and the stain on its image may prove indelible.