NEW DELHI, Aug. 16 -- The phrase both governments reached for on Saturday was the same one they have used for years: a specially privileged strategic partnership. It has never had to carry as much weight as it does now. Six months ago New Delhi agreed to stop buying Russian oil in exchange for Washington cutting tariffs on Indian goods from 50 percent to 18. Nine days ago the US Senate passed a bill that still lists India among the five largest buyers of Russian oil.

The exchange itself was slight. Russia's Foreign Ministry congratulated India on its 80th Independence Day, wishing it success, prosperity and new achievements, describing cooperation between the two countries as multifaceted with enormous potential for deepening, and noting...