President Biden announced Friday he would block the sale of U.S. Steel to Japanese-owned Nippon Steel following a yearlong review of the potential acquisition.

“We need major U.S. companies representing the major share of US steelmaking capacity to keep leading the fight on behalf of America’s national interests,” Biden said in a statement. “As a committee of national security and trade experts across the executive branch determined, this acquisition would place one of America’s largest steel producers under foreign control and create risk for our national security and our critical supply chains.”

“So, that is why I am taking action to block this deal,” Biden said.

Nippon Steel had previously indicated it could take legal action if the deal was blocked. U.S. Steel had also said it hoped Biden would approve the transaction.

Nippon Steel first announced in December 2023 that it planned to purchase U.S. Steel for roughly $15 billion. The planned transaction raised alarms among Pennsylvania lawmakers and steelworkers about what it could mean for outsourcing jobs, for union workers and for U.S. supply chains.

The president last March called it “vital” for U.S. Steel to remain domestically owned and operated. 

The Committee on Foreign Investment in the United States, which reviews certain transactions involving foreign investments, spent roughly a year examining the potential deal. While Biden publicly opposed it, the White House did not make an official announcement on whether he would block the transaction or allow it to proceed amid complicated election-year politics as he, and later Vice President Harris, courted union voters and sought to project strength on economic issues.

“As I have said many times, steel production—and the steel workers who produce it—are the backbone of our nation,” Biden said Friday. “A strong domestically owned and operated steel industry represents an essential national security priority and is critical for resilient supply chains.  

“That is because steel powers our country: our infrastructure, our auto industry, and our defense industrial base,” he added. “Without domestic steel production and domestic steel workers, our nation is less strong and less secure.”

President-elect Trump had also said he would block Nippon Steel’s efforts to buy U.S. Steel.

Updated at 8:43 a.m. EST