New Delhi, March 25 -- US President Donald Trump has sent yet another signal that he has no qualms deploying tariffs as a geopolitical weapon. As reported, he has now said the US would levy a 25% tariff on all imports from any country that purchases oil or gas from Venezuela, a country that has been under US sanctions but whose finances he evidently wants to squeeze harder.

India would be on the US radar for this punitive measure, given India's shipments of Venezuelan crude. Trump's justification is flimsy. Caracas, he alleges, has been wilfully and sneakily sending "criminals" and violent folks to America.

The US shunning it is one thing; trying to make others do likewise is another. The most glaring part of such a US policy move would...