I think demand for "crude oil" is the truth behind the US nuclear deal with India.
Crude oil was first retrived in year 1859.
1. World "had" 2 trillions barrels of crude oil out of which 50% is already consumed . 2. World needs 83 million barrels perday as on march 2005 out the remaining 1.25 trillion barrels reserve. 3 USA consumes 20 million barrels per day ie 20% of the every day's production. 4. As per the estimates the worst scenario is oil reserves will last by year 2035. 5. Indian economy is contributing "demand" to the oil.
USA wants India to consume its enery needs from "alternative" sources like nuclear etc.