ISTANBUL 

Billionaire investor Bill Ackman warned Monday that the US is on the brink of a self-inflicted "economic nuclear war" due to controversial tariffs introduced last week by President Donald Trump, who he has been a supporter of.

Ackman, who last year supported Trump’s successful campaign bid, wrote on X: “By placing massive and disproportionate tariffs on our friends and our enemies alike and thereby launching a global economic war against the whole world at once, we are in the process of destroying confidence in our country as a trading partner.”

Trump’s new tariffs, announced last Wednesday, impose a 10% base rate on all imports, affecting over 180 countries and shaking global markets. China was hit the hardest, facing 54% duties, while Beijing shot back with 34% tariffs on US goods.

Ackman stressed that “business is a confidence game” and warned that the president is rapidly losing the trust of business leaders worldwide. He added that the impact on the US and its citizens, especially low-income consumers already struggling financially, will be deeply harmful. “This is not what we voted for,” said Ackman, a hedge fund manager.

He added that if the US chooses to “launch economic nuclear war on every country in the world,” it could bring business investment to a standstill. He warned that consumers would stop spending, and the damage to America's global reputation could be long-lasting, taking “years and potentially decades to rehabilitate.”

He added that no CEO or board would feel confident making major, long-term investments in the middle of what he called “an economic nuclear war.”

Instead of the sweeping tariffs, he counseled, Trump has a chance to pause and open negotiations to address any “unfair” tariff agreements. “Alternatively, we are heading for a self-induced, economic nuclear winter, and we should start hunkering down,” he warned.