U.S. President Donald Trump intensified a trade dispute with Canada, slapping tariffs of up to 24 percent on imported softwood lumber in a move that drew swift criticism from the Canadian government, which vowed to sue if needed.

Trump announced the new tariff at a White House gathering of conservative journalists, shortly before the Commerce Department said it would impose countervailing duties ranging from 3 percent to 24.1 percent on Canadian lumber producers including West Fraser Timber Co.

“We’re going to be putting a 20% tax on softwood lumber coming in — tariff on softwood coming into the United States from Canada,” Trump said Monday, according to a tweet by Charlie Spiering, a White House correspondent for Breitbart News. A White House official confirmed the comment.

The step escalates an economic battle among neighboring countries that normally have one of the friendliest international relationships in the world. U.S. Commerce Secretary