For decades, relations between Washington and New Delhi were shaped through the prism of the cold war, when India was viewed as a client state of the Soviet Union, its largest arms supplier and one of its biggest trading partners. Even after the Soviet collapse, relations remained prickly because of accumulated mistrust and New Delhi's resentment over US sanctions over India's nuclear weapons programme.

But in recent years Indo-US ties have undergone a dramatic transformation. George W. Bush, the US president, saw India, with its democratic tradition, as a "natural ally", and was determined to bury the past.