The United Steelworkers union has filed charges with the National Labor Relations Board and is accusing U.S. Steel of undermining the union and discouraging workers from voicing skepticism about the potential sale of the company.

The union says it has raised concerns since the sale of U.S. Steel to Nippon Steel, Japan's largest steelmaker, was proposed in 2023.

The union says U.S. Steel initiated a coordinated attack to silence those views.

U.S. Steel tells KDKA that it engages employees in all business matters and the charges filed are another example of the union's attempt to thwart the sale of the company.

The latest on the potential sale of U.S. Steel to Nippon Steel

Earlier this month, President Trump said that Nippon Steel will drop its $14.1 billion bid to acquire U.S. Steel and instead "invest heavily" in the company without taking a majority stake.

The president did not reveal details of the proposed investment, and said he and other officials would later meet. 

People close to the deal were uncertain about whether Mr. Trump wants them to restructure the deal or start again from scratch  

During his final weeks in office, former President Joe Biden moved to halt the acquisition of U.S. Steel after federal regulators deadlocked on whether to approve it, saying that maintaining a strong domestic steel industry was important for U.S. national security. 

U.S. Steel and Nippon Steel each filed lawsuits over Biden's decision to stop the sale.