Nippon Steel plans to invest an additional $1.3 billion in U.S. Steel's mills as part of its strategic initiative to acquire the American steel producer. This investment will focus on upgrading two existing plants, including the West Mifflin hot strip mill, to improve yield, product quality, and energy efficiency. The Japanese steelmaker's total investment in U.S. Steel will reach $2.7 billion through 2026 if the acquisition proceeds. Nippon Steel aims to secure union support and address opposition from U.S. unions and politicians to its $14 billion takeover bid.