Legendary investor Warren Buffett likened tariffs to “an act of war” in a new interview as President Trump doubles down on his embrace of the economic strategy.

In an interview that aired Sunday on CBS News, anchor Norah O’Donnell asked Buffett about the effects tariffs will have on the economy.

“Tariffs are actually, we’ve had a lot of experience with them,” Buffett said in response. “They’re an act of war, to some degree.”

On tariffs’ impact on inflation, Buffett said, “Over time, they are a tax on goods.”

“I mean, the Tooth Fairy doesn’t pay ’em,” he added with a laugh.

Buffett said it’s important in economics to look a step ahead and ask, “And then what?”

“You always have to ask that question in economics,” he said. “You always say, ‘And then what?’”

The interview aired as Trump’s 25-percent tariffs on Canada and Mexico are slated to take effect Tuesday. Earlier on Monday, Trump announced that there was no more room for dealmaking before the 30-day delay expired.

“The tariffs, they’re all set. They go into effect tomorrow,” Trump said, adding there’s “no room left for Mexico or Canada” to make a deal before midnight.

Trump had warned last week that the tariffs will go forward after he delayed them for a month following conversations with the Canadian and Mexican leaders, during which they agreed to action to address the flow of drugs at the border.

Buffett joined O’Donnell for a documentary about his close friend, the late Katharine Graham, longtime publisher of The Washington Post.

Buffett refrained from commenting on the economy during the interview in an apparent acknowledgment of the power his words have to sway the market.

“Well, I think that’s the most interesting subject in the world, but I won’t talk, I can’t talk about it, though. I really can’t,” he said when asked for his thoughts on the state of the economy.