President Biden blocked the deal between Nippon and U.S. Steel earlier this month due to "national security" concerns.

President Joe Biden has rejected the nearly $15 billion proposed deal for Nippon Steel of Japan to purchase Pittsburgh-based U.S. Steel.

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.

President Joe Biden on Friday announced his decision to block the $14 billion sale of U.S. Steel to Japan’s Nippon Steel, citing national security concerns. The move could have serious implications in Gary,

President Joe Biden officially announced on Friday he has blocked Nippon Steel's $14.1 billion purchase of U.S. Steel, setting up a likely federal court battle.

The companies condemned the president's decision and hinted at taking legal action, while U.S. Steel's CEO accused Biden of "political corruption."

In dual lawsuits filed Jan. 6, U.S. Steel Corp. and Nippon Steel Corp. blame the Biden administration's politicizing its national-security review as well as the behind-the-scenes actions by rival Cleveland-Cliffs Inc. and United Steelworkers International President David McCall for scuttling the $14.9 billion deal.

In a joint statement, Nippon and U.S. Steel called Biden’s decision “a clear violation of due process and the law’’ and suggested they would sue to salvage their deal: “We are left with no choice but to take all appropriate action to protect our legal rights.’’

In blocking the sale to Nippon Steel, Biden said U.S. Steel "will remain a proud American company – one that’s American-owned and American-operated."

The critics’ focus on politics reflects that they are flat wrong on the merits. If the merger went through, it could leave the U.S. without ready access to sufficient volumes of specific critical steel products and the ores to make them that are necessary for our national defense and domestic infrastructure.

On Friday, President Joe Biden moved to block the long awaited $14.9 billion sale of United States Steel Corp. to Nippon Steel Corp., thus ending a saga that lasted more than a year.