By Jonathan Marcus
BBC diplomatic correspondent
Trade, bilateral relations and other economic issues will figure prominently in Japanese Prime Minister Shinzo Abe's visit to India.
Mr Abe has arrived in India for a three-day visit
But underlying his talks with Indian leaders will be the changing geo-strategic map of Asia and the desire of some countries - with Japan a prominent player - to forge a new network of relationships; if not to contain China, then at the very least to create a counter-weight to the region's rising giant.
Over recent years long-standing allies like Japan, the United States, and Australia have been renewing their defence ties.
Japan's military posture has undergone some subtle but significant changes.
Japan's armed forces have shrugged off at least some of the restrictions imposed by their constitutional commitment to a solely defensive role.
This more muscular Japan, prompted in large part by concerns over North Korea's nuclear and missile programmes, is also entertaining the idea of broader defence relationships.
Last May, on the sidelines of a regional meeting in Manila, officials from Australia, Japan and the US met for the first time with India at the table, to pursue a broad strategic dialogue.
Some commentators hailed this as the beginning of a new quadrilateral defence relationship.
But this would be premature. What was being proposed is for the moment something "far less than an alliance", Professor Richard J Samuels, of the Massachusetts Institute of Technology, told me.
His new book Securing Japan charts the changing course of successive Tokyo governments' defence thinking.
"I'd call all this a probe," he said, "but it is a probe with commitment behind it. There's a lot of interest, especially in Japan and the United States."
He says that "these countries are groping for a new set of defence relationships".
In many ways the security architecture of Asia is significantly under-developed.
There is no equivalent political-military organisation to Nato. And the post-World War II dominance of the US in the Pacific is being challenged by the rise of countries like India and China.
Asean is regarded by some as a mere talking shop
Competition and co-operation is as much economic as military but with trans-national threats like terrorism and piracy, and vital trade routes to protect, defence issues cannot be ignored.
It is interesting that Asia's largest security grouping - the Asean regional forum, which brings together the 26 member states with countries like India, Japan, Australia, Canada, the US and EU - has tried to bolster its crisis management role.
It is establishing a quick-reaction group to respond when trouble threatens; but this is perceived very much in diplomatic rather than military terms.
Such steps can be no substitute for formalised, practical relationships between key military players.
But if India is being slowly drawn into something that one day might potentially become a more formal alliance, just who would such an alliance be aimed against?
Clearly China's military modernisation is one crucial factor driving this process. But China's growing economic and diplomatic weight is also important.
China's military modernisation is a crucial factor driving the process
All four countries involved, at least in public, are quick to assert that this putative alliance is not aimed at anyone, least of all China.
Indian spokesmen are the most vocal in rejecting any idea of "containing" Beijing.
Nonetheless many analysts see such ties as a means to maintain a multi-polar Asia to balance China's growing dominance.
And military alliance or not, next month India is to host a large-scale naval exercise in the Bay of Bengal with ships from Australia, the US and Japan.