The threat comes as Trump's administration pressures pharmaceutical companies to lower drug prices for Americans.

India, which now faces among the highest tariff rates imposed by the US, called the levy "unjustified and unreasonable".

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.