The US Commerce Department has approved a tariff increase on Nippon Steel, as the Japanese steelmaker promised to fight imports to secure support for its $14.1 billion deal to acquire US Steel.

The Commerce Department imposed a 29% anti-dumping duty on Nippon Steel for selling hot-rolled steel in the United States at below-normal prices from October 2022 through September 2023, according to a preliminary ruling published in the Federal Register.

The Nov. 13 decision was part of the department’s annual administrative review of the dumping case that began in 2016, when the Big Four US steelmakers filed the complaint.

The decision was revealed on the same day that Nippon Steel promised unionized steelworkers at US Steel that it would not ship steel slabs from its foreign mills, as part of its commitment to buy the iconic American company.

The updated tariffs, if confirmed, would be significant, rising from 1.39% to 29% on Nippon Steel’s hot-rolled steel products. Hot-rolled steel is the global benchmark for the steel industry, the most widely produced alloy, and is used in everything from cars and appliances to bridge construction.

“Nippon Steel has always respected the U.S. legal system in assessing and addressing the impact of imports on U.S. domestic industry,” Nippon Steel said in an emailed statement. “It will continue to fully comply with U.S. trade remedy laws.”

The Commerce Department’s timing is unlikely to be tied to the CFIUS decision, as it was part of an administrative review of an existing dumping case, and such reviews occur annually. The previous two reviews of the case were published around the same time in each of the past two years.