United States tariffs on Mexican and Canadian imports took effect on Tuesday. The levies, set at 25 percent by US President Donald Trump, have been followed by the doubling of duties on Chinese goods to 20 percent. Levies on Canadian energy are limited to 10 percent.

President Trump's sweeping tariffs threatened to upend free trade in North America and sent shock waves through the global supply chain.

President Donald Trump reversed course on Tuesday afternoon on a pledge to double tariffs on steel and aluminum from Canada to 50%, just hours after announcing the higher tariffs, in rapid-fire moves that scrambled financial markets.