If one were to look at the conversations between Roosevelt and Churchill during WW II, one would see the 'tactical' as focused on the immediate logistics of pursuing the war against Hitler. This would be 'lend-lease', intelligence sharing, etc.
'Strategic' dialog, in comparison, is what happens afterwards. In this context the US asked Britain to give up it's colonies in order to give self-determination to more of the world. The US preferred to deal directly with the leaders of free states rather than channel diplomatic efforts through Great Britain.
The South Asian chessboard is pretty complicated. There is the India/China faceoff, the India/Pakistan faceoff, environmental and workplace safety concerns with Bangladesh, and Afghanistan in terms of India's support as a counterweight to Pakistan. Thus the US has a lot of interests in the region, and some of these are in common with India and some are not. Therefore, the US offers to bargain, but for these discussions the focus is on long term outcomes. What would be necessary in terms of long term policies, for example, to allow the Pakistan/Indian issue to settle down?
The US has a concern about global warming. India as a country with a large population is burning a lot of coal and oil, and will do more so as it grows. Therefore the US could promote the idea of a civilian nuclear power industry that would be cleaner than coal, however it would be necessary to account for the proliferation dimension of the nuclear option. This would involve not merely an agreement with the present government, but a sign-on by other interest groups that feel that they have a stake in the matter. This discussion will eventually have to be routed through those groups. This will take some time, perhaps years.
