Pentagon's FORTRESS Plan Would Keep Bases Running 90 Days Off-Grid
The Pentagon is drawing up plans to keep American military bases running for at least 90 days with no help from the civilian world — no municipal power, no city water, no functioning global supply chain.
The effort is called FORTRESS, and it is built around a blunt assumption: that a major war involving the United States would not stay overseas. Power grids could go down. Ports and rail lines could be disrupted. Factories could lose access to parts and minerals shipped from halfway around the world.
"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 said, describing the initiative he led.
The 90-Day Standard
Under FORTRESS, every major military installation in the continental United States would be expected to sustain essential operations on its own for a minimum of 90 days. That covers electricity, water, fuel and communications — the four things a base cannot function without for long.
The Defense Department had already signaled it wanted installations less dependent on commercial power. The new standard goes further by extending self-sufficiency beyond the electrical system to the other services that keep a base alive.
To get there, the initiative envisions portable nuclear reactors, large-scale battery storage and microgrids that can be islanded — disconnected from the commercial grid and run independently during a prolonged outage.
"Mission-critical power must be independent, hardened, and redundant," Parnell said. "Power is combat now. Without electricity, you lose communications, water, logistics, assembly lines and just basic military command structures."
Why Microgrids and Reactors
Most American bases draw electricity from the same utilities that serve nearby towns, and most backup generators are sized for days, not months. Diesel generators also need fuel deliveries, which is exactly the kind of outside dependency FORTRESS is trying to eliminate.
Small modular and portable reactors, still an emerging technology, would in theory let an installation generate its own power for extended stretches. Battery banks paired with on-site solar or gas generation would smooth out the gaps.
Stockpiles and Second Sources
The plan also assumes the global shipping networks the U.S. military relies on would break under the strain of a wide conflict.
"The next conflict will likely be fought on multiple fronts. Look at the geopolitics behind any major war. When that happens, global supply chains will break," Parnell said.
FORTRESS calls for strategic reserves of munitions, fuel, critical minerals, electronics, spare parts and medical supplies. Reserve targets would be set based on how fast each item gets consumed in combat and how long manufacturers would need to replace it — a calculation that has drawn fresh scrutiny since the war in Ukraine exposed how quickly artillery shells and interceptors can be burned through.
For the most critical dependencies, the initiative requires at least two qualified supply or production pathways. The goal is to make sure the loss of a single plant, supplier or specialized industrial capability cannot stop production outright. Rare earth magnets, solid rocket motors and certain microelectronics are the kinds of items that have historically traced back to one or two sources.
Turning Civilian Factories Into War Plants
Another piece of FORTRESS absorbs an existing effort, the Civil Reserve Manufacturing Network, which aims to identify commercial factories that could pivot to defense production in a crisis.
Rather than improvising after a war starts, the Pentagon wants to assess manufacturers' capabilities in advance and lock down technical specifications, cybersecurity requirements, contracting arrangements and conversion procedures ahead of time. The plan also includes recurring industrial stress tests and mobilization exercises to see whether those companies could actually hold up production through months of disruption.
It is a deliberate echo of World War II-era mobilization, when automakers retooled to build bombers and tanks — but with modern complications like software, cyber vulnerabilities and specialized tooling that cannot be improvised overnight.
Jamming, Satellites and the Two-Ocean Assumption
FORTRESS extends into space and the electromagnetic spectrum as well, with efforts to harden military communications, navigation and satellite capabilities against interference. That includes preparing forces to keep operating when GPS signals are jammed or spoofed and when space-based assets are degraded — scenarios already playing out in regional conflicts.
Parnell framed the broader shift as a break from decades of homeland defense thinking.
"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," he said, pointing to the administration's Golden Dome missile defense push and a renewed focus on the Western Hemisphere, Greenland and Panama.
Many of the specifics — cost, timelines, which bases go first — have not been made public. What has been described is the intent.
"You don't want to be making these decisions in the middle of a global multi-front conflict. We have to have a plan," Parnell said, calling FORTRESS an insurance policy for the homeland.
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