US Steel and Nippon Steel filed lawsuits on Monday challenging US President Joe Biden’s decision to block the companies’ proposed $14.9 billion merger deal, alleging the administration cited baseless national security concerns.

The two steelmakers contended that the deal would have bolstered domestic manufacturing capacity while adhering to all legal and regulatory requirements. The two lawsuits, filed in federal court, asserted that the Biden administration’s decision to halt the transaction was politically motivated rather than based on legitimate national security concerns, claiming the companies took extensive measures to address potential security issues.

The companies further alleged that the Biden administration violated the companies’ right to a fair merger review by the Committee on Foreign Investment in the United States (CFIUS) and that the review process was designed to reach a predetermined result. Additionally, sources familiar with the matter indicated that some top US officials, including Treasury Secretary Janet Yellen and Secretary of State Antony Blinken, did not believe there were sufficient national security grounds to block the deal.

Biden announced his decision to halt the acquisition on January 3. He emphasized the importance of maintaining American ownership over steel companies to ensure the industry’s strength and protect the US economy.

The US Department of Justice declined to comment on the lawsuits, while the White House defended Biden’s decision in a statement on Monday. White House Spokesperson Robyn Patterson stated: “A committee of national security and trade experts determined this acquisition would create risk for American national security … President Biden will never hesitate to protect the security of this nation, its infrastructure, and the resilience of its supply chains.”