In May, the American Primary Aluminum Association, which represents the two companies, sent a letter to Robert E. Lighthizer, the United States Trade Representative, and Wilbur Ross, the Commerce secretary, saying that an import surge from Canada was threatening the viability of their business.
Only a handful of aluminum smelters, which produce raw aluminum out of bauxite, still operate in the United States. In April, aluminum giant Alcoa idled a smelter in Ferndale, Wash., saying that production there was “uncompetitive” based on current market conditions.
Aluminum production is hugely energy intensive, and the industry has gradually migrated out of the United States toward Canada, Iceland, the United Arab Emirates, Russia, and other countries with ample petroleum, hydroelectric or geothermal power. China, which heavily subsidizes aluminum production, is also a major global producer.
Since aluminum is vital for producing planes, cars and other products, the Trump administration has seen this exodus of aluminum production as a threat to national security, though critics of that view say the United States has a ready and secure supply of aluminum in Canada, an ally that fought in Afghanistan and elsewhere alongside U.S. forces.
In a congressional hearing with Mr. Lighthizer last week, Representative Suzan DelBene, Democrat of Washington, said that closure of the Alcoa smelter had put 700 people in her district out of work and she urged the administration to step up its efforts to address Chinese overcapacity.
“It’s something we’re working on,” Mr. Lighthizer said. “The president did take a bold step when he put tariffs on. And the problem unfortunately is not just China, right, as you know well, it’s also a problem with Canada that we’re working on.”