Washington has drawn a new line in the global battle for critical minerals. The U.S. Export-Import Bank has issued a $200 million Letter of Interest to REAlloys Inc., a rare-earth company developing what could become North America’s first fully integrated mine-to-magnet supply chain. The commitment marks one of the clearest signals yet that the United States intends to rebuild the rare-earth infrastructure that China has dominated for a generation.REAlloys, now completing its merger with Blackboxstocks (NASDAQ: BLBX), plans to link every…