"The key channel by which secondary tariffs on buyers of Russian energy could impact the global economy would be through the level of energy prices," says Kieran Tompkins from the consultancy Capital Economics. If the tariffs work, they will cut the flow of Russian oil and gas to global markets.

U.S. President Donald Trump is pushing China and India to stop buying oil from Russia and helping fund the Kremlin’s war against Ukraine. Trump is raising the issue as he seeks to press Russian President Vladimir Putin to agree to a ceasefire.