WASHINGTON -- Prime Minister Justin Trudeau is vowing to keep up the fight against the never-ending effort in the United States to slap countervailing duties on Canadian softwood lumber exports.

The World Trade Organization last week ruled against the U.S., which imposed the duties in 2017 on the grounds that Canada's regulated forestry industry amounts to an unfair subsidy for Canadian producers.

Trudeau says the U.S. Department of Commerce is wrong to continue challenging the Canadian lumber industry, which he says results in higher construction costs on both sides of the border.

Construction, he says, will be a key factor in the efforts of both countries to bounce back from the COVID-19 pandemic -- particularly in the U.S., where demand for lumber significantly outstrips the domestic supply.

U.S. trade ambassador Robert Lighthizer calls the WTO decision an indictment of the organization's much-maligned dispute resolution system, which he believes has long been biased against American interests.

The ruling was the latest irritant in Canada's fraught trade relationship with the U.S., which just last month imposed new tariffs on Canadian aluminum exports in spite of the newly enacted U.S.-Mexico-Canada Agreement.

This report by The Canadian Press was first published Sept. 2, 2020.