NEW DELHI - Rain threatened to dampen the excitement around US President Barack Obama's landmark visit to India as thousands of troops prepared on Monday for a dazzling military parade where he will be the chief guest.
The first US president to attend the annual show of military might that was long associated with the anti-Americanism of the Cold War, Obama spent the first day of his visit on Sunday bonding with Prime Minister Narendra Modi and sealing a clutch of deals.
The two leaders announced plans to unlock billions of dollars in nuclear trade and to deepen defence ties, steps they hope will establish an enduring strategic partnership.
Most significant was an agreement on two issues that, despite a groundbreaking 2006 pact, had stopped US companies from setting up nuclear reactors in India and had become one of the major irritants in bilateral relations. "Mobama breaks N-deadlock," the Mail Today newspaper said on its front page, which carried a photograph of Modi and Obama hugging each other warmly.
The bonhomie was a remarkable spectacle, given that a year ago Modi was persona non grata in Washington and was banned from visiting the United States for nearly a decade after deadly Hindu-Muslim riots in a state he governed.
Obama will be chief guest at the Republic Day celebrations in the capital, where tanks, troops and floats showcasing India's cultural diversity will pass along Rajpath, an elegant lawn-bordered boulevard dating from the British colonial era that connects the presidential palace to India Gate.
Despite on-off rain and overcast skies, tens of thousands were gathered along the route for the annual spectacle.
Security was tight at the parade and across the city, where tens of thousands of police and paramilitary personnel were deployed on street corners and rooftops.
Obama's 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.
Bickering over protectionism culminated in a fiery diplomatic spat in 2013 and the abrupt departure of the US ambassador from New Delhi, who has only just been replaced.
The United States views India as a vast market and potential counterweight in Asia to a more assertive China, but has frequently been frustrated with the slow pace of New Delhi's economic reforms and unwillingness to side with Washington in international affairs.
Elected last May, Modi has injected a new vitality into the economy and foreign relations and, to Washington's delight, has begun pushing back against China across Asia.
The two leaders emerged from their talks on Sunday with a 10-year framework for defence 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.
Obama also enjoyed a close friendship with Modi's predecessor Manmohan Singh, who staked his premiership on the controversial nuclear deal that made India the sixth"legitimate" atomic power and marked a high point in Indo-US relations.
The deal failed to deliver on a promise of business for US companies because of India's reluctance to shield suppliers from liability, a deviation from international norms that reflects the memory of the Bhopal industrial disaster.
Obama will leave India slightly earlier than first scheduled to travel to Saudi Arabia following the death of King Abdullah, skipping a planned visit to the Taj Mahal.