China is now fully part of the global energy trading system, regularly importing more than 9m barrels a day of oil and a rapidly growing amount of natural gas. But Beijing faces an American assertion of power that threatens to disrupt the current pattern of trade, not least in energy. The Chinese reaction could reshape markets we take for granted.

The first American action is direct: a war of competing tariffs on trade between the US and China that affect everything from washing machines to rice and even baseballs.

The second is indirect: the US sanctions against Iran that prohibit trade between third countries and Iran including trade in oil. Initially exemptions on such trade were granted to a number of countries including India and China, but in May the US began withdrawing those exemptions.