"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.

Russia accused the United States on Tuesday of exerting illegal trade pressure on India after U.S. President Donald Trump threatened again to raise tariffs on India over its purchases of Russian oil.