President-elect Donald Trump says that he intends to block the $14.9 billion sale of U.S. Steel to Japan's Nippon Steel, adding that he will use tax incentives and tariffs to support the American-owned manufacturer. 

In a post to his Truth Social platform on December 2, Trump said that he is "totally against the once great and powerful U.S. Steel being bought by a foreign company." 

“As President, I will block this deal from happening," he vowed. "Buyer Beware!!!"

The proposed sale was first announced in December 2023, and has faced opposition from U.S. Steel union workers and federal leaders alike, including President Joe Biden and Vice President Kamala Harris. The United Steelworkers union (USW) has expressed concerns over potential supply chain issues that could crop up if the company is sold to a foreign manufacturer in Nippon Steel, as well as a lack of transparency into Nippon's finances, while the Biden administration has pointed to potential threats to national security.

USW — which had previously endorsed Harris for president — voiced support for Trump's vow to block the sale, stating, "it's clear that President Trump understands the vital role a strong domestic steel industry plays in our national security, as well as the importance of the jobs and communities the industry supports." Nippon responded in its own statement to Agence France-Press, promising to invest $2.7 billion into U.S. Steel's unionized facilities, and to "secure union jobs so that American steelworkers at U.S. Steel can manufacture the most advanced steel products for American customers." 

Under the terms of Nippon's proposed deal, U.S. Steel would keep its name, and remain headquartered in Pittsburgh, Pennsylvania. Nippon would also honor the company's existing collective bargaining agreements with USW.