Trump hikes US global tariff rate to 15 per cent

US President Donald Trump speaks during a press conference in the Brady Press Briefing Room of the White House in Washington. [AFP]

President Donald Trump raised the global duty on imports into the United States to 15 percent on Saturday, doubling down on his promise to maintain his aggressive tariff policy a day after the Supreme Court ruled much of it illegal.

Trump said on his Truth Social platform that after a thorough review of Friday's "extraordinarily anti-American decision" by the court to rein in his tariff program, the administration was hiking the import levies "to the fully allowed, and legally tested, 15% level."

The US leader had announced an initial 10 percent duty in the immediate aftermath of the Supreme Court ruling.

And Trump added that over the next few months, his administration would seek further alternative ways to impose "legally permissible" tariffs.

Saturday's announcement is the latest in a careening process that has seen a multitude of tariff levels for countries sending goods into the United States set and then altered or revoked by Trump's team over the past year.

It also appears on its face to be an attempt to circumvent the Supreme Court's latest ruling, which offered perhaps the firmest rebuke yet of the Republican leader's sweeping and often arbitrary duties, his signature international trade policy.

The new duty by law is only temporary -- allowable for 150 days. According to a White House fact sheet, exemptions remain for sectors that are under separate probes, including pharma, and goods entering the US under the US-Mexico-Canada agreement.

Trump spent much of the past year imposing various rates to cajole and punish countries, both friend and foe.

On Friday, the White House said US trading partners that reached separate tariff deals with Trump's administration would also face the new global tariff.

The conservative-majority high court ruled six to three on Friday that a 1977 law Trump has relied on to slap sudden rates on individual countries, upending global trade, "does not authorize the President to impose tariffs."

Trump, who had nominated two of the justices who repudiated him, responded furiously, alleging without evidence that the court was influenced by foreign interests.

"I'm ashamed of certain members of the court, absolutely ashamed, for not having the courage to do what's right for our country," Trump told reporters.