How does the media constantly get away with the reason for the tariffs? Canada has and continues to be a gateway for the Chinese import of steel and Aluminum. It's clearly stated within the USMCA on the matter. It's like everyone puts on blinders to the reasoning for the retaliatory effort to skirt the rules.
https://www.commerce.gov/news/press-releases/2020/01/commerce-finds-dumping-imports-fabricated-structural-steel-canada-china
China has been skirting tariffs by dumping imports to the Canadian market. It's been going on for decades, but picked up in the past 4 years.
China sells cheap to Canada, the Canadian industry then sells at a cheaper rate to the US market.