The Trump administration says it won't be pressured by trade threats from the Canadian government, responding Saturday to a warning that the northern neighbour could start targeting American industries in the event of a protracted dispute over softwood lumber.

The administration's commerce secretary issued a statement calling the threats inappropriate, and insisting they would have no effect on the U.S.'s course of action in the lumber dispute.

Commerce Secretary Wilbur Ross said the decision to slap duties on Canadian lumber was based on the facts presented — not on political calculations.

The U.S. has contended for decades that Canada's lumber companies are unfairly subsidized through cheap access to public land, and the issue has repeatedly resulted in disputes that include lawsuits, imposing duties and temporary settlements.

Its high tariffs have been struck down several times by panels of the World Trade Organization.

Commerce Secretary Wilbur Ross speaks to the media about Canadian lumber tariffs at the White House on April 25. Ross said the decision to slap duties on Canadian lumber was based on the facts presented — not on political calculations. (Andrew Harnik/Associated Press)

The Canadian government now says it wants a long-term settlement — or else. It's preparing to target specific industries in the U.S., to put pressure on those Americans backing a hard line on lumber.

Government sources have told The Canadian Press they are weighing two separate actions.

The first was revealed Friday by Prime Minister Justin Trudeau. He sent a letter to the premier of B.C., announcing he was seriously considering banning U.S. coal exports from that province and that trade experts were studying it.

Stacks of lumber are seen at NMV Lumber in Merritt, B.C., on Tuesday. Trudeau sent a letter to the premier of B.C., announcing he was seriously considering banning U.S. coal exports from that province . (Jonathan Hayward/Canadian Press)

Sources say the next step targets the state of Oregon.

The federal government has begun studying all business subsidies in that state, home to Democratic Senator Ron Wyden. Following that, the Canada Border Services Agency could examine duties on Oregon's plywood, wine, flooring, wood chips and packaging materials.

Ross brushed aside the threat.

"The decision to impose tariffs on Canadian softwood lumber was based on the facts presented, not on political considerations," he said in a statement. "If any Canadian or British Columbian official wishes to present additional information (about lumber), we will consider it carefully and impartially...

"Threats of retaliatory action are inappropriate and will not influence any final determinations. We continue to believe that a negotiated settlement is in the best interests of all parties, and we are prepared to work toward that end."