The president’s threats to slap duties on goods imported from the European Union are part of a pattern of directing the harshest penalties at the United States’ closest allies.

US President Donald Trump ramped up his tariff threats to the European Union while saying he would speak with the leaders of Canada and Mexico, as stock markets sank following a hectic weekend that saw prospects for a trade war turn into reality.

Canada, Mexico and China responded to Trump's long-promised tariffs on imports, with Canada immediately retaliating. The EU also weighed in with its reaction.