11:13 AM EST, 01/06/2025 (MT Newswires) -- United States Steel ( X ) and Japan's Nippon Steel on Monday jointly filed a lawsuit challenging President Joe Biden's decision to block their deal.

Biden last week blocked US Steel's pending acquisition by the Japanese steel giant, citing national security concerns and supply chain risks. In December 2023, Nippon agreed to purchase US Steel for $14.1 billion in cash, plus the assumption of debt.

In a joint statement, the steelmakers said they filed a petition in the US Court of Appeals for the District of Columbia Circuit, challenging Biden's decision and an "unlawful" review process by the Committee on Foreign Investment in the United States. Last month, the CFIUS referred the deal to Biden after failing to reach a consensus on whether to clear it or not.

The companies alleged that the CFIUS failed to conduct a fair review process due to Biden's "undue influence to advance his political agenda." Biden allegedly blocked the deal to "gain favor" with United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union, more commonly known as United Steelworkers, or USW.

"From the outset of the process, both Nippon Steel and US Steel have engaged in good faith with all parties to underscore how the transaction will enhance, not threaten, US national security," the companies said in the statement. "Today's legal actions demonstrate Nippon Steel's and US Steel's continued commitment to completing the transaction."

A committee of national security and trade experts decided against the proposed acquisition, a White House spokesperson said, according to Reuters. "President Biden will never hesitate to protect the security of this nation, its infrastructure, and the resilience of its supply chains," the spokesperson reportedly said.

US Steel and Nippon also filed a complaint in the US District Court for the Western District of Pennsylvania against Cleveland-Cliffs (CLF), its Chief Executive Lourenco Goncalves and United Steelworkers President David McCall. The companies claim that both individuals engaged in "illegal and coordinated" actions to prevent the deal.

"By blocking Nippon Steel's attempt to acquire US Steel, the Biden administration protected vital U.S. interests, safeguarded our national security and helped preserve a domestic steel industry that underpins our country's critical supply chains," McCall, who is president of USW International, said in an emailed statement to MT Newswires. "We are reviewing the complaint and will vigorously defend against these baseless allegations."

The steelmakers said they aim to move forward with both cases as swiftly as practicable. "We remain confident that the transaction is the best path forward to secure the future of US Steel -- and we will vigorously defend our rights to achieve this objective," the companies said.

Nippon previously committed to invest $2.7 billion in US Steel's unionized facilities, but the deal still received pushback from the United Steelworkers union. Last week, the union said the proposed merger failed to commit to guarantee long-term production or strengthen domestic capacity in integrated facilities.

Cleveland-Cliffs did not respond to a request for comment from MT Newswires.

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