MaterialsInterest-bearing debt more than doubles in a year amid refinancing effortsNippon Steel has promised to invest $11 billion in U.S. Steel by 2028. (Photo by Hiroki Endo)RIHO TAKAHASHI, NAOKI MATSUDA and AZUSA KAWAKAMIJune 23, 2026 21:36 JSTTOKYO/NEW YORK -- Nippon Steel is struggling to show the fruits of its acquisition of U.S. Steel more than a year later as rising interest rates further increase the burden of the enormous debt that the Japanese company took on to finance the deal.Read NextLatest on Materials