"Canada is a trading nation, and we will not allow North American industries to be hurt or threatened by unfair trade practices, like the diversion of steel and aluminum," Trudeau said in a statement.   

"Our businesses and workers rely on our integrated industries, and we will take strong action to defend and protect our most important trade relationships. Canada will not be used as a back door into other North American markets."

The proposed measures, which follow U.S. President Donald Trump’s Section 232 tariffs, allow the Canada Border Services Agency to investigate companies that might be trying to evade duties by slightly modifying products or assembling them in Canada. 

The measures would also give the agency greater flexibility in determining whether prices charged in the exporter's domestic market are accurate or distorted.

In a separate Section 232 development, specialty alloys manufacturer Allegheny Technologies Inc. (ATI) said it will seek an exclusion from the steel tariffs for its Allegheny & Tsingshan Stainless joint venture. 

The joint venture imports semi-finished slab from Indonesia, converts it at ATI’s Hot Rolling and Processing Facility in southwestern Pennsylvania, and finishes the coils at the joint venture’s Direct Roll Anneal and Pickle Facility, also in Pennsylvania.

In a statement, ATI chairman and chief executive Rich Harshman said the company is confident that the joint venture meets the criteria for an exclusion. 

“This joint venture, which began commercial operations earlier this year, will directly create up to 100 high-paying manufacturing jobs in western Pennsylvania and will support a significant number of workers and businesses along its U.S. supply chain, including ATI’s own flat-rolled products U.S.-based business,” Harshman said. 

“There is no, nor has there ever been a, merchant market for stainless semi-finished products (slabs) in the U.S., and the financial benefits from the joint venture directly support ATI’s important role in providing innovative materials and components for critical U.S. defense applications,” he said.