Selling United States Steel to Nippon Steel would pose a risk to national security as well as to the entire American steel industry, the United Steelworkers (USW) said in a letter to Treasury Secretary Scott Bessent.

The influential union that runs most of the steelmaker’s plants said the risks cannot be overcome in any scenario in which Nippon Steel exercises influence over U.S. Steel’s decision-making. The union called the Japanese firm a "serial unfair trader” and said it contributes to global overcapacity, echoing U.S. President Donald Trump’s often-used tough-on-trade rhetoric.

The comments indicate the union that led the push to kill the deal during former U.S. President Joe Biden’s term hasn’t budged, even as Trump shifts between several positions and awaits a review of the deal. Trump’s decision to take another look at the deal raised hopes among investors the sale might be revived, though Trump repeatedly has said he does not want Nippon Steel to hold a majority stake in U.S. Steel.