US President Joe Biden is preparing to block Nippon Steel's US$14.9 billion acquisition of U.S. Steel, a move that could impact jobs and foreign investment.

The proposed deal, announced last year, has faced significant opposition from politicians and the US Steelworkers union due to concerns about foreign control and job losses. Following the news, U.S. Steel's stock dropped nearly 20%.

Biden, along with rivals Trump and Harris, has raised national security issues. U.S. Steel has not yet received an official decision and warns that blocking the merger could result in factory closures and job cuts.

The deal is under review by the Committee on Foreign Investment in the US (CFIUS), with the next step being the receipt of CFIUS’s recommendation.