WEST MIFFLIN, Pa. — President Donald Trump announced on Friday his decision to raise the tariff rate on steel to 50%, marking a significant increase that may further inflate the costs of metal employed in the production of housing, automobiles, and other goods.

He made this announcement during a visit to U.S. Steel’s Mon Valley Works-Irvin Plant located in West Mifflin, Pennsylvania, in close proximity to Pittsburgh, where he discussed investment plans by Japan’s Nippon Steel.

The price of steel products has increased roughly 16% since Trump became president, according to the government’s producer price index.

Trump assured that U.S. Steel would remain an American entity as part of an agreement allowing Japan-based Nippon to invest in the renowned American steel producer, although limited information about the deal has been disclosed.

“We’re here today to celebrate a blockbuster agreement that will ensure this storied American company stays an American company,” Trump said as he opened an event at one of U.S. Steel’s warehouses near Pittsburgh. “You’re going to stay an American company, you know that, right?”

Trump said doubling the tariffs on imported steel “will even further secure the steel industry in the U.S.” But such a dramatic increase could push prices even higher.

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Employees, Trump supporters, local officials and others filled one of the massive warehouses on the grounds of the Irvin finishing plant to hear Trump. Giant American flags hung from the ceiling and a sign read, “The Golden Age.” Steelworkers in orange hard hats and work clothes milled about, and part of the warehouse’s cement floor was packed with huge rolled coils of shiny steel sheet produced at the plant and used for appliances, doors and other applications.

Though Trump initially vowed to block the Japanese steelmaker’s bid to buy Pittsburgh-based U.S. Steel, he changed course and announced an agreement last week for what he described as “partial ownership” by Nippon. It’s not clear, though, if the deal his administration helped broker has been finalized or how ownership would be structured.

Trump stressed the deal would maintain American control of the storied company, which is seen as both a political symbol and an important matter for the country’s supply chain, industries like auto manufacturing and national security.

Trump, who has been eager to strike deals and announce new investments in the U.S. since retaking the White House, is also trying to satisfy voters, including blue-collar workers, who elected him as he called to protect U.S. manufacturing.

U.S. Steel has not publicly communicated any details of a revamped deal to investors. Nippon Steel issued a statement approving of the proposed “partnership” but also has not disclosed terms of the arrangement.

State and federal lawmakers who have been briefed on the matter describe a deal in which Nippon will buy U.S. Steel and spend billions on U.S. Steel facilities in Pennsylvania, Indiana, Alabama, Arkansas and Minnesota. The company would be overseen by an executive suite and board made up mostly of Americans and protected by the U.S. government’s veto power in the form of a “golden share.”

In the absence of clear details or affirmation from the companies involved, the United Steelworkers union, which has long opposed the deal, this week questioned whether the new arrangement makes “any meaningful change” from the initial proposal.

“Nippon has maintained consistently that it would only invest in U.S. Steel’s facilities if it owned the company outright,” the union said in a statement. “We’ve seen nothing in the reporting over the past few days suggesting that Nippon has walked back from this position.”

Unionized steelworkers said there is some split opinion in the ranks over Nippon Steel’s acquisition, but that sentiment has shifted over time as they became more convinced that U.S. Steel would eventually shut down their Pittsburgh-area plants.

Clifford Hammonds, a line feeder at the plant where Trump spoke, said at the very least the deal will help upgrade the aging plant and help increase production.

“It’s putting money back into the plant to help rebuild it, because this plant is old, it’s falling apart. We ain’t really producing as much as we should be because, like I said, this place is old. It’s falling apart. We need some type of investment to fix the machines that we’ve got working,” Hammonds said.

Other U.S. Steel union members said recruiting new employees has been difficult because of the uncertainty around the Nippon Steel deal and the future of the plants.

No matter the terms, the issue has outsized importance for Trump, who last year repeatedly said he would block the deal and foreign ownership of U.S. Steel, as did former President Joe Biden.

Trump promised during the campaign to make the revitalization of American manufacturing a priority of his second term in office. And the fate of U.S. Steel, once the world’s largest corporation, could become a political liability in the midterm elections for his Republican Party in the swing state of Pennsylvania and other battleground states dependent on industrial manufacturing.

Trump said Sunday he wouldn’t approve the deal if U.S. Steel did not remain under U.S. control and said it will keep its headquarters in Pittsburgh.

In an interview on Fox News Channel on Wednesday, Pennsylvania Republican Rep. Dan Meuser called the arrangement “strictly an investment, a strategic partnership where it’s American-owned, American run and remains in America.”

However, Meuser said he hadn’t seen the deal and that “it’s still being structured.”

Pennsylvania Republican Sen. David McCormick called the plan “great” for the domestic steel industry, Pennsylvania, national security and U.S. Steel’s employees. He initially opposed Nippon Steel’s first proposal to buy U.S. Steel for $14.9 billion after it was announced in late 2023.

In recent days, Trump and other American officials began touting Nippon Steel’s new commitment to invest $14 billion on top of its $14.9 billion bid, including building a new electric arc furnace steel mill somewhere in the U.S.

Pennsylvania’s other senator, Democrat John Fetterman – who lives across the street from U.S. Steel blast furnace – didn’t explicitly endorse the new proposal. But he said he had helped jam up Nippon Steel’s original bid until “Nippon coughed up an extra $14B.”

Gov. Josh Shapiro, a Democrat who is seen as a potential presidential candidate, had avoided publicly endorsing a deal but said this week that he was “cautiously optimistic” about it.

Chris Kelly, the mayor of West Mifflin, Pennsylvania, where U.S. Steel’s Irvin finishing plant is located, said he was “ecstatic” about the deal, despite the lack of details. He said it will save thousands of jobs for his community.

Associated Press writer Yuri Kageyama in Tokyo contributed to this report.