Wealthy business leaders are turning on US President Donald Trump over his plan to impose a colossal set of tariffs on America’s trading partners, as losses mount on stock markets around the world.

Billionaire investor Bill Ackman, who endorsed Trump’s 2024 presidential bid, warned Sunday that going ahead with the new tariffs was tantamount to launching an “economic nuclear war.”

On Wednesday, Trump said he would impose significantly higher “reciprocal” tariffs on dozens of countries that have the highest trade imbalances with the United States.

In a post on X, Ackman said “business investment will grind to a halt, (and) consumers will close their wallets” if the new levies do indeed come into force. “We will severely damage our reputation with the rest of the world that will take years and potentially decades to rehabilitate,” he added in the post, which was viewed 10.6 million times.