A $6.27 billion replacement GPS control system was canceled this year, aircraft receivers remain years away, and GAO says fragmented Pentagon management is hampering efforts to protect U.S. forces from a threat already demonstrated in Ukraine.
WASHINGTON — For more than two decades, the Pentagon has been trying to solve a problem that has since stopped being hypothetical.
America’s military depends heavily on the Global Positioning System to navigate ships, aircraft and vehicles, coordinate communications and guide precision weapons. Adversaries have meanwhile demonstrated that GPS signals can be jammed, spoofed or otherwise disrupted.
The Department of Defense has spent tens of billions of dollars trying to make that system harder to defeat and developing alternatives for when it is.
According to a new Government Accountability Office report released Tuesday, considerable work remains.
GAO describes GPS as the military’s principal source of positioning, navigation and timing information, but also warns that the Pentagon’s dependence on it creates a potential “single point of failure.” The department has spent more than 20 years developing a more secure and jam-resistant military GPS signal known as M-code, yet modernization has repeatedly encountered delays across satellites, ground-control systems and the equipment necessary for weapons and military platforms to actually use the signal.
The stakes are no longer confined to acquisition schedules.
Russia has used GPS jamming during the war in Ukraine to degrade some U.S.-provided precision-guided munitions, according to GAO, while both Russia and Ukraine have used spoofing to interfere with legitimate GPS signals.
Research cited by GAO found intensified GPS jamming in eastern Ukraine reduced the effectiveness of one type of GPS-dependent precision-guided munition by as much as 80 percent. Another munition remained disrupted as much as 40 percent of the time even after countermeasures were employed.
The Pentagon is therefore racing not merely to improve GPS, but to ensure American forces can continue operating when GPS is unavailable.
It is doing so while still trying to finish a modernization effort that began around the turn of the century.
Satellites Since 2005, Receivers Still Coming
The military’s M-code capability depends upon three pieces working together: satellites capable of transmitting the signal, a ground system capable of controlling the constellation, and receivers installed in weapons and military equipment capable of using it.
The first M-code-capable GPS satellites have been in orbit since 2005.
Development of the Next Generation Operational Control System, known as OCX, began in 2010. Development of newer receiver equipment began in 2017.
Previous GAO investigations have documented schedule delays reaching a decade or longer and cost increases reaching billions of dollars.
The government watchdog was raising alarms about OCX by at least 2015, when it reported persistent cost and schedule growth, a high defect rate and concerns that unrealistic estimates were limiting Pentagon oversight. GAO’s 2015 report is available here.
Eleven years later, the Pentagon pulled the plug.
The Space Force formally accepted OCX from contractor Raytheon in July 2025 following years of development and testing. But acceptance came with waivers and deviations related to technical shortcomings.
Among them was an unmet requirement involving “time-steering,” the mechanism used to maintain accurate time dissemination through the GPS constellation. Pentagon testing officials also considered the system’s cyber survivability a high-risk area requiring continued mitigation and investment.
Integrated testing then uncovered still more problems.
Space Force officials later said the difficulties spanned numerous capability areas and potentially put existing military and civilian GPS capabilities at risk.
By January 2026, the government had spent approximately $6.27 billion on OCX, including Raytheon funding and government testing and program-support costs.
Three months later, DOD canceled it.
Space Force concluded that attempting to complete OCX posed greater risk than continuing to upgrade the GPS control system that OCX had been designed to replace. The Space Force’s account of the termination is available here.
The Pentagon had effectively spent years and billions developing a replacement for its old GPS control system, accepted that replacement with unresolved deficiencies, and then concluded that modernizing the old system was the safer option.
The Replacement for the Replacement
DOD is now pursuing what it calls Architecture Evolution Plan Modernization, or AEP-M, a multiphase modernization of the existing GPS Operational Control Segment.
But changing direction carries consequences of its own.
The Space Force had planned to use OCX capabilities to launch, check out and operate the next generation of GPS IIIF satellites. Those satellites and their software were being prepared around OCX.
Now the existing control system has to be modified to handle them instead.
GAO says the decision creates schedule risk for incorporating the new satellites into the GPS constellation. The first ten GPS IIIF satellites were already averaging nine months of delay against a revised December 2024 delivery schedule as of September.
The first satellite was projected for delivery in July 2027, while ground-control capability is needed in time to support planned launches beginning in 2028.
It is another dependency in a modernization program full of them.
And satellites that can broadcast M-code are only useful if American weapons can receive it.
Aircraft Remain a Problem
GAO found that development and fielding of M-code receiver equipment continue to face software, funding, technical and integration problems, particularly aboard aircraft.
Integrating the new receivers into aircraft requires tying them into flight software and satisfying airworthiness requirements, making aviation among the most difficult pieces of the modernization puzzle.
One Air Force program, the Embedded GPS Inertial Navigation System-Modernized, or EGI-M, lost one of its contractors after the company failed to provide what officials considered a realistic updated development schedule.
The remaining contractor underestimated the complexity of software associated with security and airworthiness certification, according to GAO.
Funding shortages created another problem: the contractor could not maintain the staff necessary to complete development on schedule.
Production decisions for EGI-M variants used by the Navy’s E-2D and Air Force F-22 are now estimated for mid-2028. A decision on the F/A-18 variant is projected for 2030.
Initial EGI-M fielding is expected in March 2032.
The Navy, meanwhile, is developing an interim receiver to provide M-code capability to aircraft while it waits for the longer-term system.
There has been progress elsewhere. The Army and Navy are fielding M-code-capable and multi-PNT receivers in some ground vehicles, ships and Army aircraft, and all the services are pursuing systems capable of combining GPS with alternative navigation information.
Those alternatives are becoming increasingly important.
When GPS Goes Dark
DOD is building what amounts to a navigation toolbox for a battlefield where GPS can no longer be assumed.
Some systems would obtain positioning signals from satellites in low-Earth orbit. Others could navigate without satellites at all.
Inertial systems measure a vehicle’s direction, acceleration and orientation. Visual-navigation systems compare camera imagery against stored maps. Other technologies navigate by comparing measurements against maps of Earth’s magnetic or gravitational fields.
Still others look upward.
Modernized celestial-navigation systems can determine location using stars, planets and even artificial satellites whose orbits are known.
The Pentagon is also deploying backup timing systems, including regional clocks and increasingly small atomic clocks, because disruption of GPS can affect far more than knowing where a vehicle is located. Loss of GPS timing can interfere with military communications and networking.
GAO’s illustration on page 22 depicts the intended result: GPS satellites operating alongside low-Earth-orbit constellations, celestial navigation, inertial sensors, visual navigation, magnetic and gravity navigation and alternative timing sources while adversaries attempt jamming, spoofing, cyberattacks and direct attacks against satellites.
The technology exists in various stages of maturity.
Getting all of it into the right weapons at the right time appears to be another matter.
Everyone Is in Charge
That may be the most consequential finding buried inside GAO’s highly technical report.
Congress created a Positioning, Navigation and Timing Oversight Council to coordinate DOD’s sprawling PNT enterprise. But individual military services retain authority over the budgets funding their respective programs.
The council can establish priorities and make recommendations.
The services control the money.
GAO found that this fragmented structure makes it difficult to synchronize programs that depend upon one another.
A receiver card might be developed by one organization. Another program develops the receiver containing it. A military service then has to integrate that receiver into an aircraft, ship or vehicle. Munitions fired by those platforms may operate on yet another modernization schedule.
The result can be technologically sophisticated pieces arriving at different times.
Internal meeting records reviewed by GAO show that the problem has not gone unnoticed.
Officials discussed inadequate Air Force funding for aviation receiver programs, and program officials attributed missed development goals partly to “chronic underfunding.”
At a May 2025 PNT Oversight Council meeting, one official identified what may be the simplest description of the organizational problem: there was a need to “designate a single owner to the entire PNT value chain.”
DOD has since consolidated several aviation receiver and M-code efforts into an Air Force-managed joint program office. GAO found that consolidation has produced closer reviews of costs, schedules, technical risks and performance and could serve as a model elsewhere.
But the broader enterprise remains fragmented.
GAO concluded that under the existing structure, DOD “lacks reasonable assurance” that its PNT investment decisions are addressing pressing warfighting needs.
Two Decades of Warnings
The new report does not arrive in isolation.
GAO warned in 2021 that M-code remained years from widespread use and that receiver delays were producing ripple effects across weapons programs. Read GAO-21-145.
In 2022, auditors found that Pentagon databases used to manage GPS modernization contained incomplete or inaccurate information. DOD was ultimately planning to integrate modernized GPS equipment into roughly 700 weapon systems, making reliable schedules and coordination particularly important. Read GAO-22-105086.
In 2023, GAO again reported ground-system delays and questioned other portions of the modernization strategy. Read GAO-23-106018.
And in September 2024, GAO reported that significant challenges remained across the space, ground and user-equipment segments of the modernization effort. Read GAO-24-106841.
Two years later, the ground system examined in those reports no longer exists as a development program.
GAO’s latest report puts the broader history in unusually stark terms: DOD has worked for more than two decades and spent tens of billions of dollars laying the foundation for fully modernized GPS and complementary navigation systems, yet “considerable work remains” before those capabilities are fielded.
GAO issued three recommendations calling on the Army, Navy and Air Force to assess where GPS modernization and complementary PNT programs should be consolidated and to develop consolidation plans where doing so would improve strategic alignment.
DOD agreed with all three recommendations.
The Army maintains that its modernization efforts are already well coordinated and that it has found no duplication, but told GAO it will participate in a broader Pentagon assessment and develop a consolidation plan where appropriate.
The Navy and Air Force likewise agreed to examine consolidation.
The technology race, meanwhile, is unlikely to wait for the organizational chart.
The Pentagon began developing a GPS signal resistant to jamming more than two decades ago. The first satellites capable of transmitting it reached orbit in 2005. Since then, wars have supplied real-world evidence of what happens when precision weapons encounter an enemy capable of interfering with satellite navigation.
The United States now possesses satellites broadcasting the hardened signal, weapons waiting for modernized receivers, alternative navigation technologies under development and a new program to upgrade the old ground-control system after abandoning its $6.27 billion replacement.
What it still does not have, according to GAO, is assurance that all those pieces will arrive where they are needed when the next battlefield starts interfering with GPS.
Sources
- GAO-24-106841 — GPS Modernization: Delays Continue in Delivering More Secure Capability for the Warfighter, Sep. 2024
- GAO-23-106018 — GPS Modernization: Space Force Should Reassess Requirements for Satellites and Handheld Devices, Jun. 2023
- GAO-22-105086 — GPS Modernization: DOD Needs to Ensure Reliable Data to Manage and Oversight Its Modernization Effort, 2022
- GAO-21-145 — GPS Modernization: DOD Continuing to Develop New Jam-Resistant Capability, But Widespread Use Remains Years Away, Jan. 2021
- GAO-15-657 — GPS Modernization: DOD Faces Challenges in Sustaining Capabilities and Achieving Acquisition Goals, 2015
- U.S. Space Force — USSF Terminates Program for the GPS Next Generation Operational Control System, Apr. 2026
