U.S. President-elect Donald Trump vowed to block Nippon Steel’s planned purchase of U.S. Steel in a Truth Social post on Monday night. He pledged to revitalize U.S. Steel with tax incentives and tariffs to restore its prominence. Japan’s largest steelmaker agreed to acquire U.S. Steel last December, but the deal has faced resistance from labor unions and President Joe Biden. Nippon Steel has pledged to strengthen U.S. Steel while supporting American industry, supply chain resiliency, and national security. U.S. Steel shares dropped over 15% this year, while Nippon Steel shares declined more than 4%.