More than once, the developing relationship between the United States and India, driven in part by mutual unease over China's assertive rise, has been called one that could define the 21st century. Ties between the two large nations with open societies were often cool during the Cold War era - when New Delhi tilted towards Moscow and Washington towards Islamabad - but have dramatically surged since then US President Bill Clinton travelled to India in 2000. Before him, only three US presidents had visited India while in office: Dwight Eisenhower, Richard Nixon and Jimmy Carter. In contrast, every subsequent president has made it to India and Mr Barack Obama, twice. Mr Donald Trump's visit maintains the record.

Mr Trump's trip, which comes as he approaches the intense phase of his re-election campaign, was high on useful optics. Prime Minister Narendra Modi, by receiving the US leader in his home state of Gujarat, ensured that crowds thronged either side of Mr Trump's route to the city to visit the ashram of India's independence hero Mahatma Gandhi. A rally Mr Trump addressed at a newly built cricket stadium, touted as the world's largest for South Asia's favourite sport, exceeded its capacity of 100,000. In Agra, the Taj Mahal was closed off for the Trump family. Meeting for the eighth time in four years, Mr Trump accepted Mr Modi's embrace repeatedly.