President Donald Trump on Tuesday took on his next international challenge: retaliating against Canada, whose leaders have apparently “outsmarted” U.S. politicians for years.

The U.S. Commerce Department announced late Monday that Trump’s administration will impose new tariffs on softwood lumber imports from Canada.

Early Tuesday morning, Trump tweeted that Canada “has made business” for dairy farmers “very difficult” as well.

“We will not stand for this. Watch!” he posted.

Canada has made business for our dairy farmers in Wisconsin and other border states very difficult. We will not stand for this. Watch! — Donald J. Trump (@realDonaldTrump) April 25, 2017

“People don’t realize Canada’s been very rough on the United States,” Trump said during a White House roundtable with farmers Tuesday afternoon. “Everyone thinks of Canada as being wonderful and so do I, I love Canada, but they’ve outsmarted our politicians for many years.”

“Do you fear a trade war with Canada?” a reporter asked.

“No, not at all,” Trump said. “They have a tremendous surplus with the United States. Whenever they have a surplus, I have no fear.”

He went on to claim “virtually every country” has a trade surplus with the United States.

“We have massive trade deficits,” Trump said. “So when we’re the country with the deficits, we have no fear.”

Canadian Prime Minister Justin Trudeau said on Tuesday that his country’s economic connection to the United States is “not just a one-way relationship,” according to a report by Canadian broadcaster CTV.

“There are millions of good U.S. jobs that depend on smooth flow of goods, services and people back and forth across our border,” he said. “You cannot thicken this border without hurting people on both sides of it.”