US President Donald Trump responded with fury to Friday’s Supreme Court ruling that he lacked the power to unilaterally set tariffs on imports, denouncing individual justices as he vowed to continue a global trade war that has kept the world on edge for a year.

Saying he was undeterred by what he repeatedly called a ridiculous ruling, Trump announced an immediate new 10% tariff on imports from all countries, on top of any existing tariffs, and then issued a proclamation putting them into effect. The law allows him to impose a levy of up to 15% for 150 days, although it could face legal challenges.

The court’s landmark 6-3 ruling upended the leverage Trump and his trade envoys have wielded over foreign governments at negotiating tables to reshape diplomatic relations and global markets.

The ruling briefly sent US stock indexes surging, before ending modestly higher as analysts warned of renewed confusion in global markets while they await Trump’s next moves.

Hours after the ruling, Trump signed an executive order repealing the tariffs that the court struck down, and he also issued a proclamation imposing a 10% duty on most goods imported into the US for 150 days, granting exemptions for certain items including critical minerals, metals and energy products, the White House said.

TRADE DEALS, REVENUE IN QUESTION

The ruling called into question the trade deals Trump’s envoys have negotiated in recent months under the threat of high tariffs. It left open the fate of the $175 billion Trump has collected from US importers under what the court said was his incorrect reading of the law.

“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 at the White House, complaining that foreign countries were ecstatic and “dancing in the street.”

He insinuated, without evidence, that the majority of the court caved to foreign influence: “They’re very unpatriotic and disloyal to our Constitution. It’s my opinion that the court has been swayed by foreign interests and a political movement that is far smaller than people would ever think.”

Since returning to the White House 13 months ago, Trump has said he had what the court summarised as the “extraordinary power to unilaterally impose tariffs of unlimited amount, duration, and scope.” Citing a national emergency, he said the International Emergency Economic Powers Act (IEEPA) meant he could set tariffs at any rate he chose.

The court grounded its opinion, which was written by Chief Justice John Roberts, with a quote from the US Constitution: “The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises.”

The argument by the Trump administration that it had identified a war-like emergency to justify a loophole failed to persuade the court.

“The Government thus concedes, as it must, that the President enjoys no inherent authority to impose tariffs during peacetime,” Roberts wrote.

“And it does not defend the challenged tariffs as an exercise of the President’s war-making powers. The United States, after all, is not at war with every nation in the world.”

Despite the court’s bluntness in ruling the president had exceeded his authority, Trump told reporters: “It’s ridiculous, but it’s OK, because we have other ways, numerous other ways.”

ECONOMIC UNCERTAINTY RISES

After a year of Trump’s often ad hoc tariff announcements whipsawing markets and the global economy, the ruling and Trump’s response reintroduced a hefty dose of uncertainty that economists, investors and policymakers had hoped was in the rearview mirror.

“I think it will just bring in a new period of high uncertainty in world trade, as everybody tries to figure out what the US tariff policy will be going forward,” said Varg Folkman, analyst at the European Policy Centre think tank.

US Treasury Secretary Scott Bessent said the court ruling could have mixed results.

“The Supreme Court has taken away the President’s leverage, but in a way, they have made the leverage that he has more draconian because they agreed he does have the right to a full embargo,” Bessent told “The Will Cain Show” on Fox News.

“We will get back to the same tariff level for the countries. It will just be in a less direct and slightly more convoluted manner,” he said.

In announcing his new temporary 10% tariff, Trump became the first president to invoke Section 122 of the Trade Act of 1974, which allows the president to levy tariffs of up to 15% for up to 150 days to fix “fundamental international payments problems.” That, too, could draw legal challenges. Such tariffs can only be extended with Congress’s authorisation.