The added tariffs that President Donald Trump imposed on India to pressure it to stop purchasing Russian oil could have ripple effects on the global market.

This week, Trump said he was raising the tariff on goods imported from India from the previously announced 25% rate to 50% as a penalty for India’s purchases of Russian oil, which help finance Vladimir Putin’s war in Ukraine. Such secondary tariffs, placed on a third party to pressure an adversary, are an untested tool of diplomacy.