WASHINGTON (Reuters) - U.S. Treasury Secretary Janet Yellen said on Wednesday that Nippon Steel's blocked acquisition of U.S. Steel received a "thorough analysis" by an interagency national security review body that was sent to President Joe Biden.

They also filed a lawsuit in federal court in Pittsburgh against rival steelmaker Cleveland-Cliffs Inc. and CEO Lourenco Goncalves, as well as United Steelworkers President David McCall, alleging coordinated anticompetitive and racketeering activities designed to allow only Cliffs to acquire U.S. Steel.

By blocking a Japanese company’s takeover of U.S. Steel, President Joe Biden said he was protecting good jobs in the American heartland. He may be putting them at risk instead.

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 Japanese firm’s planned purchase of its U.S. rival was blocked last week by President Joe Biden after a year of diplomatic tension, political debate and lobbying efforts from the companies and unions. Biden, who had previously said he opposed the tie-up, cited national-security risks, despite Japan being a close ally.

Nippon Steel Chief Executive Eiji Hashimoto says the top Japanese steelmaker is standing firm on its proposed $15 billion acquisition of U.S. Steel

Nippon Steel and U.S. Steel are filing a federal lawsuit challenging the Biden administration’s decision to block a proposed nearly $15 billion deal for Nippon to acquire Pittsburgh-based U.S. Steel

President-elect Trump has also opposed Nippon Steel's $15 billion acquisition of U.S. Steel, which President Biden blocked last week.