U.S. President Donald Trump said on Monday he will "substantially" raise tariffs on Indian exports to the United States, arguing that New Delhi is buying “massive amounts” of Russian crude and reselling part of it on the open market for profit while the war in Ukraine continues. The president did not specify the new tariff rate or a timetable for implementation. Trump’s threat intensifies pressure applied last week, when a 25% duty on Indian goods came into force. On Sunday, White House deputy chief of staff Stephen Miller accused India of effectively financing Russia’s war by purchasing oil and noted that the country now rivals China as one of Moscow’s biggest energy customers. Indian government officials told Reuters over the weekend that the country will keep importing Russian barrels despite Washington’s warnings. Russian deliveries, offered at sanctions-discounted prices, account for about 35% of India’s crude supply, making the South Asian nation the largest buyer of seaborne Russian oil. Prime Minister Narendra Modi, addressing separate trade matters, urged citizens to favor domestically made products but gave no indication of curbing energy ties with Moscow. The prospective tariff hike threatens to strain a bilateral trade relationship already unsettled by broader U.S. protectionist measures, including a 145% levy on Chinese goods that took effect in April. Trump has floated duties of up to 100% on countries that continue oil commerce with Russia unless a Ukraine cease-fire is secured. Markets are now watching for details on how steep the new charges on Indian shipments will be and whether New Delhi adjusts its energy strategy in response.