Defence co-operation, especially in weaponry, has been steadily expanding between India and the United States for some time. On this trip, the 10-year-old defence framework agreement was revised and renewed for another 10 years, and it was agreed that some projects to develop and produce weapons jointly would be begun. Bilateral co-operation on counter-terrorism is also likely to increase, extending it to go beyond intelligence sharing to working together through joint operations. On climate change and clean energy, too, the focus during the talks in this visit shifted from putting pressure on India to limit its greenhouse gas emissions to working together to promote renewal energy and solar power in particular.
But it was the leftover business of the United States-India civilian nuclear agreement that attracted most attention. Although the last United Progressive Alliance government had staked its future on the deal in 2008, and the United States fought tooth and nail in multilateral forums to "normalise" India's nuclear power, New Delhi got cold feet when it came to implementing the deal. Amid commemoration of the Bhopal gas tragedy, a nuclear liability law was passed that was an outlier by world standards, and which caused many American companies, such as GE and Westinghouse, to withdraw from the race to build reactors in India. The inability to operationalise the nuclear deal was a major irritant in Washington.
In the agreement on nuclear power reached between Mr Obama and Prime Minister Narendra Modi, it is not clear if the problem has been completely solved. A government-to-government assurance on liability law, such as this agreement features, is not likely to bind courts in the absence of legislation - and may not reassure companies. But it is at least a step towards removing the liability law as an irritant. Meanwhile, on other issues, both counties gave ground - the United States agreed multilateral inspection of facilities was sufficient, and India agreed to make up a disaster fund from Union government revenues. Mr Obama's commitment to better relations was on display when he rescheduled the State of the Union address - and when he sat in a drizzle watching the Republic Day parade. Mr Modi, too, has shown considerable enthusiasm for growing closer to the United States. These three days in New Delhi marked an important stage in Indo-US relations, going beyond the political symbolism of the trip.