- The Pentagon is preparing U.S. military bases to keep operating for at least 90 days without outside support as it prepares for the possibility of a major war that could cripple power grids, disrupt supply chains and threaten critical infrastructure on American soil. The new requirement is part of FORTRESS, a broader military initiative aimed at ensuring American forces can continue fighting even if the civilian systems they depend on are disrupted, according to documents reviewed by Fox News Digital. "We don't want to rely on standard civilian municipal infrastructure to run our national defense. We just simply can't. It's an intolerable risk," Pentagon chief spokesperson Sean Parnell told Fox News Digital. The Pentagon is also laying the groundwork for civilian factories to shift to defense production during a crisis, while preparing alternative supply chains and strategic reserves to keep weapons, fuel and other essential materials flowing. "Power is combat now. Without electricity, you lose communications, water, logistics, assembly lines and just basic military command structures," Parnell said. Under FORTRESS, every major military installation in the continental United States would be expected to sustain essential operations independently for at least 90 days, including access to electricity, water, fuel and communications. The requirement reflects a broader shift in how the Pentagon is preparing for threats to the American homeland, including the possibility that a major conflict could disrupt the infrastructure supporting military operations inside the United States. "I realized that a lot of the way we think about homeland defense was built around the antiquated assumption that two oceans would protect us," Parnell said. "President Trump understands that world is gone, and he's already paved the way for new thinking: Golden Dome, a renewed focus on the Western Hemisphere, Greenland, Panama." A central concern is the military's reliance on civilian