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

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.

President Joe Biden’s decision to reject a bid by Nippon Steel to acquire U.S. Steel isn’t the first time friction over trade and investment has irked Washington’s closest ally in Asia

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.

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 last week capitulated to uneconomic thinking by blocking Nippon Steel’s purchase of U.S. Steel. That decision will ultimately harm Minnesota’s Iron Range.

U.S. Steel and Japan’s Nippon Steel sued the United States government on Monday in a last-ditch attempt to revive their attempted merger after President Biden blocked it last week on the basis that the transaction posed a threat to national security.

Nippon Steel, whose multibillion-dollar proposal to buy struggling US Steel was blocked by President Joe Biden last week, says it is considering taking legal action against the US government.

The companies also filed a second suit against the head of the United Steelworkers union and steel company Cleveland Cliffs, claiming the two worked together to block the U.S. Steel and Nippon deal. Download the FREE WPXI News app for breaking news alerts.