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 companies argued in a lawsuit announced on Monday that Biden violated the Constitution by blocking the merger via a sham national security review that deprived the companies of their right to a fair process.

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 the Japanese firm that had sought to acquire it are suing the Biden administration after the president announced he was blocking a proposed deal for the iconic American manufacturer.