President Donald Trump wrote on social media that he would no longer allow the Canadian aircraft maker Bombardier to sell in the United States.

He said that if the company wanted the American market it should manufacture there, adding that the United States should not be treated as a piggy bank, and referred to revoking certification for the aircraft concerned.

The remarks came hours before Canada's retaliatory tariffs took effect. Ottawa is imposing what it calls dollar-for-dollar duties of up to 50 percent on $20 billion of American goods.

Bombardier ranks among the leading makers of business jets. The United States is one of its largest markets, and its component supply chain spans both countries.

Aircraft certification has generally been treated as a technical process governed by safety standards. Its invocation as a trade instrument has drawn concern within the aviation industry.

The United States and Canada maintain closely linked supply chains in vehicles, energy and agricultural goods. The wider the tariff coverage, the more manufacturers on both sides are exposed to higher costs.

Asian carriers and lessors also operate Bombardier types and are watching for any change to certification and maintenance arrangements.