The U.S. military has used global positioning system (GPS) satellites in its operations for many years — flying planes, coordinating soldiers’ movements, targeting enemy forces and synchronizing communication systems. This dependence has become a weakness.
In a real conflict, GPS signals can be jammed, faked or attacked outright, either from the ground or in space. The Department of Defense knows this, and it has spent the past several years working on a different approach. Defense leaders don’t want to rely on GPS alone and are building systems that can keep working even when GPS goes dark.
The Pentagon calls this “assured” navigation. This does not necessarily imply abandoning GPS but ensuring that a mission is able to proceed even when GPS becomes unavailable or unreliable.
Today’s warfare depends on accurate time and position data. The pilots must know their exact position. The ground forces must do likewise. Under normal conditions, GPS handles this well. But an adversary who can knock out or distort that signal can turn a precise military into a lost one.
The question the Pentagon is now asking isn’t just how accurate its GPS is, but what happens when troops can’t use it at all.
Layering backup systems
There’s no single technology that can fully replace GPS everywhere. Instead, the military is combining several: other satellite signals, ground-based radio beacons, precise internal clocks and self-contained navigation instruments that don’t need any outside signal at all.
Those self-contained instruments, built from sensors that track acceleration and rotation, work by tracking how a vehicle or aircraft moves from a known starting point, the way sailors once tracked position using speed and heading before satellites existed. They tend to drift off course the longer they run, so they aren’t a perfect substitute on their own. Paired with other tools, though, they give crews something on which to fall back.
GPS doesn’t just tell troops where they are, it also keeps clocks in sync across the military’s radios, sensors and networks. If that timing signal disappears, coordinated systems can fall out of step with each other, even when no one’s navigation is affected.
Because of this, the military is investing in more reliable onboard clocks that can keep accurate time on their own for a while if outside signals are lost.
Real-world tests
This isn’t just theoretical. In 2024, the Air Force flew a C-17 cargo plane using a magnetic-navigation system as its main method of navigation instead of GPS. This navigation system uses the differences in the Earth’s magnetic field much like how a compass points to north, but with great accuracy. It became the first system to be flown on an American military plane using this technology as its main navigation system.
The U.S. Army has also provided backup navigation systems for troops and vehicles in the case that GPS signals become blocked or jammed. For years, this kind of backup navigation was treated as a nice-to-have, something to fall back on if GPS ever failed. That’s changing.
As the military relies more on autonomous systems, drones and networked equipment, a GPS outage in the field could cascade into a much bigger problem. Losing a single signal shouldn’t be able to take down an entire mission.
That’s why defense planners increasingly build backup navigation and timing into new systems from the start, rather than adding it later.
GPS will continue playing a highly important role in how the U.S. military operates, and modernizing it is still part of the plan. But resilience means more than a powerful satellite network. It also means giving troops and equipment the tools to know when their information can be trusted and backup options to keep going when that trust breaks down.
As new systems are increasingly built with this resilience in mind from day one, reliable navigation and timing without GPS is becoming less of a specialized concern and more of a basic requirement for keeping U.S. forces effective on future battlefields.
