Three years ago, India ramped up its imports of Russia’s oil. It was a move that benefited both countries — and, in a way, the global economy.

Now President Trump is demanding that India reverse course and quit its cheap Russian oil habit or face debilitating tariffs. What would it take for India to do what Mr. Trump wants?

India’s leaders have already made clear that they will not obey the American president’s demand. Its foreign ministry called the penalty “unfair, unjustified and unreasonable,” and said that “India will take all actions necessary to protect its national interests.”

But legally and technologically, weaning itself from Russian oil is not out of the question.

Before the war in Ukraine, India imported just 1 percent of its oil from Russia. When Europe stopped buying from Russia as punishment for its full-scale invasion, India, like China, seized the chance pick up its crude at a discount worth several dollars a barrel. ICRA, an Indian rating agency, estimated that play saved Indian companies $13 billion over two years.

Quietly, this had pleased everybody. The Biden administration, which barred American companies from importing most Russian energy products, worried that too successful an embargo would upset global oil prices. Rerouting Russian crude kept the markets relatively stable; Europe was able to buy fuels refined in India; and Indian companies made a profit along the way.

Now Mr. Trump has raised this workaround as a weapon of trade war. On Wednesday he signed an executive order imposing an additional 25 percent tax on imports of Indian goods, because, he posted on Truth Social, India profited from people “being killed by the Russian War Machine.” When that penalty goes into effect, on Aug. 27, it will double an already steep tariff, demolishing the business plans of any company with a stake in trade between India and the United States.