One of the most important aspects of the recent dramatic shift in US-India relations has been the convergence in the two states' narratives about Asia. It's easy to forget that this change is palpable not just over a four-decade period, but even in the past six years alone.

In 2009, early in his first term, President Barack Obama agreed to a controversial joint statement with China in which the two sides promised to work for 'peace, stability and development in South Asia', including 'the improvement and growth of relations between India and Pakistan'. Earlier that year, India had lobbied furiously, and successfully, to prevent the US Special Representative for Afghanistan and Pakistan, the late Richard Holbrooke, from including either India or Kashmir in his remit, as the Obama Administration had initially sought.

These signals elicited irritation and anger in Delhi, particularly over the notion that Beijing might be accorded a tutelary role over India, something that affected both India's security and its status.

One former Indian ambassador to the US wrote that Obama's 'bending over backwards before the Chinese was an act of appeasement', and writer C Raja Mohan said: 'we have no interest in supporting a US-Sino condominium'. When then Prime Minister Manmohan Singh visited Washington the next year, the joint statement declared 'a shared vision for peace, stability and prosperity in Asia, the Indian Ocean region and the Pacific region', but there wasn't much substance to this. The Carnegie Endowment's George Perkovich wrote a detailed study concluding that US and Indian strategy in Asia was fundamentally divergent, so 'bilateral relations should not be used to contain China'.

Fast-forward to 2015, and things look rather different.

In the just-released US National Security Strategy (NSS), India receives prominent and adulatory mention: 'we support India's role as a regional provider of security', and 'see a strategic convergence with India's Act East policy and our continued implementation of the rebalance to Asia and the Pacific'. As Ariq Rafiq noted, this amounts to acknowledgment of India as 'regional hegemon'.

By contrast, the 2010 NSS had noted merely that 'will seek to work with India to promote stability in South Asia', a subtle but significant difference to the provision of security, and no more than was promised to Pakistan. The 2010 Quadrennial Defence Review had gone a little further, stating that, 'as its military capabilities grow, India will contribute to Asia as a net provider of security in the Indian Ocean and beyond', but this promise was still couched in the future tense. The largely vacuous nature of these official documents means that even subtle changes in wording and emphasis can denote relatively significant changes in policy.

Between 2010 and 2014, New Delhi responded positively but cautiously – some would argue timidly – to US outreach, with both countries spurred on by perceptions of Chinese assertiveness. Under the government of Prime Minister Narendra Modi, the shift has been more noticeable. The US-India joint statement that emerged from the September meeting between Obama and Modi made two extremely important references to Asia.

The first was its explicit comparison between India's 'Act East' policy and the US 'rebalance'. Indian officials had previously been wary of endorsing the rebalance for fear of provoking China, so it was striking that they would now accept an implicitly favourable parallel with India's own engagement in Asia. Second, the statement noted joint concern about the South China Sea. Whereas previous such statements had exhorted freedom of navigation in general terms, India's willingness to mention the sea by name indicated a new willingness to confront China. Modi then doubled down on his visit to Vietnam in October and at the East Asia Summit in November where even Vietnam and the Philippines, both claimants in that dispute, did not mention it

Then, on the occasion of Obama's visit to New Delhi for India's Republic Day celebrations last month, the US and India released a far-reaching 'Joint Strategic Vision for the Asia-Pacific and Indian Ocean Region', which mentioned the South China Sea and endorsed 'India's interest' in membership of APEC (China and Russia followed suit in February). Joshua White and Peter Lavoy called it a 'remarkable' statement, and argued 'Indian elites...increasingly suggest that India must embrace its Asian identity and play an active role in regional institutions'.

Some have taken a more sceptical view. Hugh White, writing in the Interpreter last week, argued that the trip was intended to boost the pivot and that 'it didn't work', because 'India is not willing to make the preservation of US primacy its principal strategic aim in Asia'. But this is a high bar to set. India doesn't need to make US primacy its main objective. It can take a range of other steps, from aligning itself to US allies to strengthening a diplomatic consensus against China, that together contribute to that primacy in a more diffuse, politically acceptable manner.

What changed between 2009 and 2015?

We can identify several factors: China's own behaviour in Southeast and South Asia, the US decision to devote greater diplomatic and military attention to Asia, and a change of government within India. These things can, of course, regress. China could aggressively seek to court India, splitting it from the US and her Asian allies; the US could become preoccupied with challenges in the Middle East and Eastern Europe, or move closer to Beijing as a result of a crisis (say, in the Korean Peninsula); and India's government could grow distracted itself, by Pakistan or Afghanistan, or decide it has been moving too fast for prudence.

Moreover, areas of disagreement will remain.

A much-vaunted solution to the impasse over Indian regulations on civil nuclear commerce, agreed during Obama's trip, appears to be shot through with holes. More broadly, India will fight anything it sees a threatening accommodation with Pakistani proxies in Afghanistan, it largely sides with Russia and Iran and on Syria, it is outright sympathetic to Russia's invasions and annexations in Europe, and, as Srinath Raghavan described in The Hindu last week, worries about being cut out of Sino-American deals on climate change and world trade. Rupa Subramanya has pointed to intellectual property as an especially thorny issue, and Ian Hall surveyed others last month. These are not trivial problems. But the last 15 years of US-India relations suggest there are structural dynamics at work. The bilateral relationship has stalled but rarely has it backslidden, and Modi has several years to push US-Indian convergence to such a degree that it would be intellectually and practically difficult for a successor to reverse.

India's sudden appointment of S Jaishankar as its foreign secretary, the senior-most diplomat in the Indian Foreign Ministry, is a sign of intent. Jaishankar was serving as India's ambassador in Washington and before that in Beijing, and played a prominent role in the Modi-Obama meetings. As he noted in a speech in January 2014, 'the US has to overcome its inclination to view ties through the lens of alliance practices', but added that 'Indians perhaps have to indulge themselves less in compulsive ambiguity'.

As that ambiguity is progressively shed, we can expect even more Indian engagement with US allies in the region, more naval exercises, more Indian attention to the South China Sea, and deeper Indian involvement with the economic and security architecture of Asia.

Photo courtesy of the White House/Pete Souza