Why GPS III, and what comes after it, still falls short in modern war

With the final GPS III satellite scheduled to launch in March, the United States is completing the most significant upgrade to its positioning, navigation, and timing (PNT) infrastructure in more than a decade. 

GPS III delivers improved accuracy, stronger signals and enhanced anti-jam capabilities for military users. By any technical measure, it is a better system than what came before.

But does it go far enough? 

Military analysts, researchers, think tanks and government watchdogs have warned for years that America’s GPS modernization is not keeping pace with real-world security threats. Those concerns are increasingly echoed on Capitol Hill, where lawmakers have pressed the Department of Defense and Space Force on whether current GPS plans are sufficient for the threat environment U.S. forces are likely to face.

This skepticism is well founded. GPS III improves performance, but it does not resolve the deeper vulnerabilities of a satellite-centric PNT architecture operating in modern war. Adversaries are no longer focused on attacking satellites alone; they are increasingly targeting receivers, where GPS remains the most exposed. Closing that gap will require a far more layered and resilient approach to PNT than what is currently planned. For that to happen, responsibility ultimately sits with the U.S. government, particularly the Space Force, which defines requirements and acquisition priorities, and Congress, which controls funding and modernization timelines. Industry and operators can innovate at the margins, but they need faster updates and clearer direction from government stakeholders. That, in turn, requires the U.S. government to rethink its assumptions about developing resilient PNT and recognize that uncontested satellite signals are a relic of a bygone era.

A system built for a different threat model

GPS III represents an iterative update rather than a paradigm shift, improving accuracy, extending service life and strengthening resistance to jamming through higher signal power and spot beam technology. While these enhancements improve reliability in contested environments, they don’t fully address sophisticated jamming threats or close the gap with competing systems like BeiDou.

Advances in modern conflict have outpaced the threat model GPS III was built around.

Today’s adversaries do not need to defeat GPS globally or destroy satellites in orbit. Instead, they rely on persistent, localized disruption at the receiver level using mobile jammers, spoofing systems and electronic warfare integrated into broader campaigns. These techniques are inexpensive, highly scalable and already in widespread use. In this environment, the limiting factor is not satellite performance alone, but dependence on a single space-based signal. GPS III hardens the system at the margins, but it does not fundamentally change that dependence.

GPS IIIF is an evolution, not a solution

Looking beyond GPS III, the Space Force is moving forward with GPS IIIF, with the first launches expected to begin in 2027. 

GPS IIIF continues the incremental modernization approach, focusing on survivability and protected military access. The satellites introduce Regional Military Protection (RMP), which concentrates GPS signals over specific areas to boost anti-jamming performance in contested regions. Beginning with SV13, the satellites will use the LM2100 Combat Bus, incorporating updated cyber protections and improved power systems. 

It is worth noting that RMP is the most significant satellite-side anti-jam enhancement planned for GPS IIIF, with public descriptions indicating very large improvements in protected-signal performance compared to legacy GPS. Even so, it does not eliminate GPS denial as an operational reality: Adversaries can and do jam GNSS locally by targeting the receiver environment, a pattern now routinely observed in contested zones and modern conflicts. Controlled Reception Pattern Antenna equipped receivers can materially reduce the effects of interference, but they do not guarantee immunity, especially against strong or close-in jamming. In practice, RMP raises the interference threshold, but it does not change the fundamental susceptibility of weak GNSS signals to local RF denial. 

For these reasons, GPS IIIF remains an evolutionary upgrade within the same architectural framework. It does not fundamentally change how GPS is structured or how dependent U.S. and allied forces remain on a single, predictable constellation. It strengthens GPS, but it does not eliminate the strategic risk of over-reliance on it.

R-GPS and the question of alternatives

The Resilient GPS (R-GPS) effort was conceived as a pragmatic experiment: Could smaller, lower-cost satellites provide a meaningful augmentation to GPS when signals are degraded or denied? Rather than replacing GPS, R-GPS explored how a proliferated architecture might improve resilience without waiting for a generational leap in technology.

In its fiscal 2026 budget request, the Space Force chose not to continue R-GPS as a standalone program, arguing that it was insufficiently transformative to justify a formal program of record. But Congress has taken a different view. Lawmakers added new funding in the House defense bill to preserve elements of the effort, citing the urgent need to improve PNT resilience in contested environments and directing the DoD to articulate a broader, integrated PNT architecture spanning space, ground, and user equipment.

This divergence underscores a deeper tension in U.S. PNT strategy. The Space Force acknowledges the need for more resilient and proliferated architectures, yet continues to anchor near-term planning around GPS IIIF and incremental upgrades. Congress, meanwhile, appears increasingly unwilling to accept a future in which diversification is perpetually deferred. The result is a growing recognition that resilience will likely come from a multi-layered solution, even if no single program yet defines that path. Adversaries are already designing around current and planned GPS improvements, so continued reliance on modest upgrades risks leaving U.S. forces exposed.

The result of GPS III will be uneven effects across platforms and partners, precisely the fragmentation adversaries seek.

This does not mean the constellation itself is irrelevant. However, GPS remains a relatively small, predictable system that is optimized for global coverage rather than regional reinforcement or rapid reconstitution.

What resilient PNT actually requires

True resilience requires a broader shift in how positioning, navigation and timing are designed and employed. Assured PNT in modern conflict cannot depend on any single system.

A resilient PNT architecture must include:

• Layered architectures: Combine GPS with other space-based, terrestrial and non-GNSS systems so that disruption of any single layer does not result in mission failure.
• Co-equal alternatives: Terrestrial timing networks, low-frequency navigation systems and other non-space-based approaches should be integrated into operations rather than treated as backups of last resort.
• Receiver-level autonomy: Enabling platforms to detect interference, authenticate signals and operate through disruption using inertial navigation, sensor fusion, and degraded-mode procedures. Additionally, leveraging the network of global receivers to map interference patterns and geolocate emitters, creating a collaborative threat picture that enhances situational awareness across the system.
• Doctrine that assumes disruption: Training and operational planning should be built around the expectation that GPS may be degraded or unavailable in contested environments.

These steps do not replace GPS, but they will ensure it remains usable when adversaries actively seek to deny it.

A call to rethink assumptions

GPS was built for a world in which satellite signals were largely uncontested, but modern war does not respect that assumption. Completing GPS III is necessary, but it is not sufficient.

China’s approach to BeiDou underscores the risk of standing still. Rather than relying on a single global signal, China has invested in layered space-based and terrestrial PNT capabilities designed to sustain operations even when individual systems are degraded. This contrast highlights a growing strategic asymmetry — not in satellite quality, but in resilience by design.