President Joe Biden decided to block the $14 billion takeover of US Steel by Japan’s Nippon Steel even though some top US officials did not believe there were sufficient national security grounds to kill the deal,

The suit, filed in the U.S. Court of Appeals for the District of Columbia, alleges that it was a political decision and violated the companies’ due process.

U.S. Steel and Japan’s Nippon Steel sued the United States government on Monday in a last-ditch attempt to revive their attempted merger after President Biden blocked it last week on the basis that the transaction posed a threat to national security.