U.S. Steel’s CEO says his company will close steel mills if its planned $14.1 billion sale to Nippon Steel is not completed.

Chief executive David Burritt told The Wall Street Journal that the Japan-based company has pledged to invest $3 billion into the company to maintain its older mills.

If the deal collapses, U.S. Steel would likely also move its headquarters out of Pittsburgh, he said, and planned investment in older mills will not happen.

“We wouldn’t do that if the deal falls through,” Burritt said in an interview with the Journal. “I don’t have the money.”

Nippon Steel, one of the world’s largest steelmakers and a top supplier to the American auto industry, announced the proposed deal last December.

Earlier this week, Vice President Kamala Harris telegraphed her opinion that U.S. Steel should remain domestically owned — coinciding with the White House’s earlier opposition. Former President Donald Trump also came out against the deal last month.

The United Steelworkers union castigated Burritt for his statement, saying the deal would allow Nippon Steel to gut U.S. Steel’s operations to benefit its steel mills in Japan.

“(Burritt’s) reckless statements and mismanagement are the only true obstacles to U.S. Steel remaining a sustainable steel company,” the union said.

Fairfield is the site of one of the company’s mills, with a $412 million electric arc furnace that began production in 2020, which can produce as much as 1.6 million tons of steel a year.

The project was originally shut down in Dec. 2015 due to unfavorable market conditions, but was announced again in 2019.

The furnace employs a mix of mini-mill and integrated mill technology. Electric arc furnaces make steel from melted scrap metal instead of iron ore and can operate with fewer workers. They are also easier to stop and restart than traditional blast furnaces that must operate continuously to avoid damage, making them flexible to market demands.

The company, founded in 1901, has deep roots in Alabama and was once the largest employer in Birmingham, with about 15,000 people on the payroll at its peak.