Firing the opening salvos of a trade war, Donald Trump said his reasons were simple: stop “illegal aliens” and put an end to the flow of fentanyl, a deadly opioid, on to America’s streets.

Both of these “national emergency” issues, the US president believes, will be solved by sweeping tariffs inflicted on America’s three largest trading partners.

Here are six charts to help explain the origins of Mr Trump’s burgeoning trade war.

The fentanyl crisis

Mr Trump says illegal street fentanyl, believed to kill 75,000 Americans a year, is one of the central reasons behind the new tariffs.

The synthetic opioid, which is 50 times more powerful than heroin and much easier and cheaper to produce, is now the leading cause of death among people aged 18 to 45.