President Donald Trump said Monday he will "substantially" raise the tariff on Indian exports to the United States, arguing New Delhi is buying large volumes of discounted Russian crude and reselling some of it at a profit. The move, announced on his Truth Social account, intensifies pressure on a key trading partner as the White House seeks to curb revenue that Moscow can deploy in its war against Ukraine. Trump did not specify a new rate, but the statement comes on top of a 25 % border tax he imposed last week that is due to take effect on 8 August. India is the world’s biggest buyer of seaborne Russian oil, importing roughly 1.75 million barrels a day in the first half of 2025, according to trade data cited by Reuters. India’s foreign ministry called the U.S. threat "unjustified and unreasonable," saying the country will take "all necessary measures" to protect its economic interests. Officials in New Delhi argue that purchases from Russia help stabilise domestic fuel prices after traditional suppliers diverted cargoes to Europe. The latest warning deepens an already fraught trade relationship and adds further uncertainty for Indian refiners and exporters as Washington weighs wider secondary sanctions on buyers of Russian energy.