"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.

Brazilian goods imported by the United States will soon carry one of the highest tariffs imposed by President Donald Trump, but that will not likely derail Latin America's largest economy, due to ample exemptions and stronger trade ties with China.