Claiming the U.S. has been "taken advantage of" under the Clinton-era NAFTA trade deal, President Trump Monday night opened a trade war with Canada, announcing a retroactive 20 percent "tax" on lumber imports, and promising a similar tax on Canadian milk.

"Canada has treated us very unfairly," the president said in impromptu remarks at a reception for conservative journalists. "We have been taken so advantage of," he said, speaking it the Roosevelt Room.

Commerce Secretary Wilbur Ross, who accompanied the president into the reception, said that the "countervailing duty" would be retroactive 90 days. He said that was when Canada was warned to stop subsidizing their lumber industry. The countervailing duty is meant to offset the subsidy.

"They were on notice," he said.

Trump hinted at the coming trade war last week.

The president put a jobs spin on the decision, which he had planned to announce Tuesday. "It's going to mean that we're doing lumber in our country," he said.

What's more, he said that deregulation efforts are already underway at the Environmental Protection Agency and the Interior Department to open the door to companies logging federal lands.

"We're going to actually do our own lumber," he said. "We will have access to great amounts of lumber," said Trump.

The president added that logging virgin but aging forests should help them recover. "By doing what we're doing, we're improving our forests."

The tax on specialized milk, used for cheese making, is expected to follow.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at