US President Joe Biden has vetoed Nippon Steel's $14.9- billion takeover bid for its American rival, US Steel. Amid bipartisan opposition to the merger, DW asks why US politicians and regulators are concerned.

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

Biden, President-elect Donald Trump and a politically-influential labour union had voiced opposition to Nippon Steel's acquisition of U.S. Steel, which helped build the Empire State Building and arm allied forces in World War Two.