STORY: Donald Trump has defended his use of tariffs, and dismissed concerns about market volatility sparked by the global trade turmoil.

Speaking to a gathering of business leaders in Washington on Tuesday, the U.S. president said his trade policy was already showing results:

“We have car companies that are not building in Mexico now, thKey’re building in the United States, some of them the plants were already started and they stopped construction and now they’re going to build in the United States. It was very unfair that they build in Mexico and sell them across the border with no tax, no nothing.”

In the audience were around 100 CEOs, and some of them may be feeling growing unease.

They’ve all seen some $4 trillion wiped off the value of U.S. stocks in recent weeks, amid fears over the impact of the trade war.

Businesses have also been concerned by the volatility of the tariffs, which have been variously imposed and delayed, raised and lowered.

On Tuesday there was more of that, with turmoil over duties on Canadian metals.

Early in the day, Trump said he would double levies to 50%.

He was responding to a move by the Canadian province of Ontario to impose its own tariffs on electricity supplied to America.

Hours later, Ontario dropped the move, and Trump said U.S. duties would stick at 25%.

The fresh day of turmoil drove another down day for stocks, outweighing glimmers of hope over a Ukraine ceasefire.

More big firms, including the retailer Kohl’s, also warned that the darkening economic outlook was hitting sales.

In the end, the Dow Jones index closed the day down another 1%.

But if that worries Trump, it didn’t show on Tuesday:

“The tariffs are having a tremendously positive impact, they will have and they are having.”

Trump said his tariffs would generate a lot of money for the U.S. and could be raised even higher in the days ahead.