Beyond the symbolism of President Barack Obama being the first US president to be the chief guest at India's Republic Day, his second visit to India in four years promises to galvanise India-US ties. There is also a great deal of speculation about who gains more from the visit - Prime Minister Narendra Modi who is said to have staged a diplomatic coup with his invitation to Obama or a lame-duck US president half-way through his second and final term in office.
But, the real significance of the visit is the fact that Obama would be meeting Modi in a formal setting less than four months after he came calling to Washington and the two vowed to "Chalein Saath Saath: Forward Together We Go."
It would give them an opportunity to check how far they have come on the ambitious road they charted and put India-US ties back on track after months of drift over the Khobragade affair, a stalled nuclear deal, trade issues and a lot more.
"It's a really big deal," as Rick Rossow, Wadhwani chair in India in US-India policy studies at the Centre for Strategic and International Studies, a leading Washington think tank put it at a media preview of the trip.
It shows the US officials are again looking at it as a 20, 30-year relationship, ready to help India become a stronger friend and partner and willing to spend the time and energy to fix some of the problems from the past, he said.
"So it is extremely significant for the president to go back to India a second time, to do it only as an India trip, to be the guest for Republic Day. The symbolism of all this is tremendous," Rossow said expecting to see "some pretty big announcements."
Officials from both sides have been scrambling to tick things outlined in their September vision statement when Modi came quickly, seizing the hand of friendship extended by Obama, without begrudging denial of a US visa for nearly a decade.
Underlining the importance of the visit, Secretary of State John Kerry at the cost of some international embarrassment, chose to skip the Paris unity rally after the attack on Charlie Hebdo satirical magazine, to keep his date with Modi at the Vibrant Gujarat Summit.
Kerry indicated that at least four broad issues - climate change, the Indo-US civil-nuclear agreement and defence and economic ties -- would be on the summit agenda.
US Undersecretary of Defence Frank Kendall, the Pentagon's point person for the bilateral defence relationship, is making his fourth trip to India this week to give a push to their Defence Trade and Technology Initiative (DTTI), ahead of Obama's visit.
As part of DTT, co-production and co-development of two critical defence systems - drones, and equipment for the C-130 transport military aircraft built by Lockheed Martin - are reported to be on the table.
A Contact Group set up by Modi and Obama at their September summit on advancing the implementation of civil nuclear deal has already held a couple of rounds to untangle the thorny issue of India's tough liability
law.
Since the September summit, the two sides have exchanged a series of high-level visits and held dialogues to advance the growing partnership.
These have included the first-ever India-US Technology Summit, Higher Education Dialogue and meetings of their Science and Technology Joint Commission and Information and Communications Technology Working Group.
Thus even if any big ticket announcements or "deliverables" elude the summit, the visit would have notched a major success by rekindling and giving a momentum to India-US ties.