In a filing to the WTO dated December 20, but only published Wednesday, Canada requested so-called "consultations" with the United States over its use of anti-dumping and countervailing duties.
Washington frequently slaps such punitive tariffs on imports it deems are subsidised or otherwise priced in a way that leads to unfair competition, including announcing late on Tuesday charges of up to 10 percent on paper used to print newspapers and books.
These duties are permitted under international trade rules as long as they adhere to strict conditions, and disputes over their use are often brought before the WTO's Dispute Settlement Body.
The Canadian complaint pointed to a slew of US "measures relating to anti-dumping or countervailing duty investigations, reviews or other proceedings, which are inconsistent with its WTO obligations."
In its complaint, Ottawa listed more than 100 examples of wrongdoings it alleged that Washington had committed in its dealings not only with Canada but also with a long line of other trade partners, including China, India, Japan, Mexico, South Africa and the European Union.
Among other things, the document reiterated a long-running Canadian complaint over US anti-dumping duties imposed on Canadian softwood lumber imports.
Washington reacted angrily to the filing.
"Canada's new request for consultations at the WTO is a broad and ill-advised attack on the US trade remedies system," US Trade Representative Robert Lighthizer said in a statement.
"US trade remedies ensure that trade is fair by counteracting dumping or subsidies that are injuring US workers, farmers, and manufacturers," he said, insisting that "Canada's claims are unfounded and could only lower US confidence that Canada is committed to mutually beneficial trade."
He stressed that if the United States removed the duties listed in the Canadian complaint, "the flood of imports from China and other countries would negatively impact billions of dollars in Canadian exports to the United States."
Canadian exports of steel and aluminium products would take a $9.0 billion hit, while its wood and paper product exports would shrink by $2.5 billion, the statement said.
"Canada's claims threaten the ability of all countries to defend their workers against unfair trade," Lighthizer said, insisting that "Canada's complaint is bad for Canada."
Canada's request for consultations marks the first step in the WTO dispute system, and is aimed at giving the parties a chance to talk things through and resolve their differences without moving forward with litigation.
If the consultations fail to resolve the dispute within 60 days, the WTO can create a panel of experts to review the case.
Canada is also embroiled in tense talks with the United States to amend the North American Free Trade Agreement (NAFTA), which President Donald Trump demanded be renegotiated to get a better deal for US businesses and consumers.
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