Trump's tariffs on Canada, Mexico and China suggest he is willing to risk a global trade war. The main thing that could stop him would be a stock market selloff.

What to know as President Donald Trump imposes steep new tariffs on imports from Canada, Mexico and China, prompting retaliation and countermeasures.

But Mr Trump’s most incendiary claims are reserved for China. The Communist Party, he says, “has subsidised and otherwise incentivised” Chinese firms to “export fentanyl and related precursor chemicals that are used to produce synthetic opioids sold illicitly in the United States”.

Donald Trump is the first president to use the International Emergency Economic Powers Act to impose tariffs, teeing up likely legal battles that will test his executive authority.