Beneath a remote Pacific island that few have ever visited, the United States and Japan have turned their gaze toward the deep ocean floor, where vast rare earth deposits may hold the key to reshaping the world's most consequential supply chains. At a White House summit earlier this year, the two nations quietly committed to exploring what would be the deepest seabed mining operation ever attempted, driven less by adventure than by the strategic imperative of reducing dependence on China's dominance over critical minerals. The announcement is as much a declaration of geopolitical intent as it