Nippon Steel says it plans to make an additional investment of at least 1.3 billion dollars in United States Steel’s two mills.
The Japanese steelmaker’s acquisition of the US firm is still in the works, although the deal was agreed in December last year.
The extra spending will go toward a mill in the state of Pennsylvania and another in Indiana.
Nippon Steel says it will build new facilities and improve blast furnaces to boost competitiveness.
The Japanese firm had officially announced its plan to invest 1.4 billion dollars in US Steel to create jobs.
The additional investment will also contribute to environmental sustainability.
Labor unions in the US steel industry are opposed to the deal, and US President Joe Biden and former president Donald Trump have sided with the labor unions.
The issue has featured in the campaign agenda of the upcoming US presidential election.
Nippon Steel hopes to finalize the acquisition by December.