"Certainly the relationship has consolidated. And it is on a much better trajectory. But there is need for both countries to continue to engage in how we can build on the gains that we have made," Shankar told PTI.
The India-US relationship has deepened and expanded across a very broad spectrum -- political, strategic and economic, she said.
"Initially, the relationship began to grow in the economic field in the early 90s after the liberalisation in India because there were new economic opportunities which had not existed before. And then we saw that with the visit of (then) President (Bill) Clinton there was a greater political interest in India," she said.
This was taken further by former President George W Bush, particularly in his second term when the nuclear cooperation initiative was launched and that became "in a sense a vehicle for transforming the relationship," said Shankar, who will complete her tenure tomorrow and will be succeeded by Nirupama Rao.
Under the Obama administration, the two countries have completed various negotiations, including on reprocessing of spent fuel, she said when asked about the progress made on the landmark treaty between the two countries.
Shankar also noted that India's National Investigation Agency was given access to David Headley, who has confessed to his involvement in the Mumbai attacks, for questioning for almost a week, that revealed the full dimension of the conspiracy with regard to the 26/11 strikes.