WASHINGTON: US President Donald Trump 's decision to take precipitate action in directing the assassination of a top Iranian general complicates India's delicate ties with Tehran, already under strain because of Washington's relentless sanctions against a country that has had civilisational ties with New Delhi going back millennia.The US strike took place barely a week after India's external affairs minister S Jaishankar visited Tehran to review ties, with the two sides agreeing to accelerate development of the India-backed Chabahar project after Washington gave New Delhi what it termed a "narrow exemption" to allow access to land-locked Afghanistan subject to Iran's Revolutionary Guards Corps (IRGC) not participating in the project.Chabhahar, which means "four springs" on account of its clement weather, was called Tis when Alexander the Great marched through the region. It is barely 100 kilometres from Gwadar, a Pakistani port developed with Chinese assistance, on which the Islamabad-Beijing axis has pinned its strategic and economic hopes.Long before Pakistan came into existence, the legendary 10th century Persian scholar-explorer-historian -- chronicler Al-Biruni wrote that the sea coast of India began at the port of Chabahar.But following Washington's frayed ties with Iran -- a country that was a US ally before the Islamic Revolution in 1979 - India has had to re-adjust its own relations with Tehran even as it seeks to maintain strategic ties with US and Israel, whose strong partnership is in part responsible putting Iran in the doghouse.The primarily Shia Iran is also at odds with other mostly Sunni monarchies in the Gulf, including its regional rival Saudi Arabia, making India's task of navigating the divide even more precarious.There was a time Iran was the primary oil supplier to India, but New Delhi has had to shut down the spigot under pressure from the US., which has now emerged as a principal energy source even as it has become an energy-surplus nation able to export oil and gas halfway across the world. US exports to India are poised to cross $ 8 billion this year, accounting for nearly ten per cent of its buying, while Iranian supply is being whittled down to zero.In fact, India has had to fight hard to convince the US of its equities in Chabahar, whose access into land-locked Afghanistan also helps Washington which like New Delhi has enormous stakes in the stability of the landlocked country."We recognise that Chabahar potentially plays an important role as a lifeline to Afghanistan in terms for India to be able to export humanitarian supplies and potentially helping Afghanistan diversify its export opportunities. That was the reason that drove the Chabahar exemption, and we continue to support it," a US official said last month explaining the American waiver.All that could come under threat if the region collapses into a broader war. There is also the small matter of more than 5 million Indian expatriates working in the Gulf. It will be 20 years this August since India had to evacuate 170,000 Indian nationals from Kuwait and Iraq - in what is regarded as the largest civilian airlift in history - following a regional war.