President Donald Trump imposed an additional 25% tariff on India as punishment for importing Russian oil, according to a document posted on the White House website — an escalation of his trade battle with New Delhi and his first use of so-called secondary sanctions on countries the US says are fueling Moscow’s war machine.

Trump has now imposed a total of 50% tariffs on goods imported from India, and his earlier threat of levying an extra 10% for the country's membership in the Brics grouping, which includes China, Russia and South Africa as founding members, still stands.

As the president pursues his goals on Russia and trade, America’s relationship with an important partner in Asia could end up as collateral damage.