India, Jan. 5 -- In the US-India relationship, trade and geopolitics have clashed, an old fault line has been reopened by US President Donald Trump's renewed warning about tariffs, which links trade penalties to India's ongoing purchases of Russian oil. The comments are made at a delicate time when diplomatic messaging is already strained due to previous claims and counterclaims and negotiations are still in progress.

Although no fresh details of a direct call were officially disclosed, Trump's public references to Prime Minister Narendra Modi suggest recent communication or at least an assumed understanding between the two leaders. Trump portrayed Modi as someone aware of Washington's displeasure, framing the relationship in personal te...