Obama reveals nuclear deal on India trip
"Ultimately it's up to the companies to go forward, but the two governments came to an understanding," he added.
Signalling warmth and determination to take ties to a higher level, Modi broke with protocol to meet and bear-hug Obama as he landed in New Delhi, then referred to him as Barack. It was a remarkable spectacle, given that a year ago Modi was persona non grata in Washington and was denied a visa to the United States.
Between a working lunch that included kebabs made with lotus stem, figs and spices and an evening banquet where Obama spoke a smattering of Hindi, the two leaders got down to talks.
Read MoreIndia's Modi making 'extremely promising' strides: World Bank chief
They emerged with a 10-year framework for defense ties and deals on cooperation that included the joint production of drone aircraft and equipment for Lockheed Martin Corp's C-130 military transport plane.
Other deals ranged from an Obama-Modi hotline -- India's first at a leadership level -- to financing initiatives aimed at helping India use renewable energy to lower carbon intensity.
But Modi cautioned that work was still needed to create a solid partnership between the world's two largest democracies.
"We have to convert a good start into lasting progress. This requires translating our vision into sustained action and concrete achievements," he said, standing next to Obama.
On Monday, Obama will be the first U.S. president to attend India's Republic Day parade, an annual show of military might long associated with the anti-Americanism of the Cold War. He will also host a radio show with Modi.
His presence at the parade at Modi's personal invitation marks the latest upturn in a roller-coaster bilateral relationship that just a year ago was in tatters.
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Obama reveals nuclear deal on India trip