The U.S. Department of Commerce on Thursday set final duties on Canadian softwood lumber after finding that imports were being unfairly subsidized and dumped in the United States, escalating a trade dispute with Canada in the midst of NAFTA trade talks.

The decision imposes anti-dumping and anti-subsidy duties affecting about $5.66 billion worth of imports of the key building material.

Canada called the measures ¡°unfair, unwarranted and deeply troubling¡± and said it was considering its options, including legal action through the North American Free Trade Agreement (NAFTA) and the World Trade Organization (WTO).