US military receiving F-35s built for upgrade, but without new radar

The F-35 Joint Program Office (JPO) has declined to confirm or deny reports that Joint Strike Fighters are being delivered to the US military without installed radars, reportedly due to ongoing complications with a critical modernization effort. Nonetheless, multiple strands of publicly available information strongly suggest that this may indeed be the case, TWZ reports.

The US military had begun receiving F-35s without radars, citing an unnamed source. According to the media reports, deliveries of radar-less aircraft began in June 2025, with all F-35A models delivered to the US Air Force since that time reportedly affected. The report did not elaborate on how or why the decision was made to accept aircraft in this configuration. Foreign customers—who continue to receive jets equipped with the older AN/APG-81 radar—are said not to be impacted.

The AN/APG-85 radar is a central component of the broader Block 4 modernization package, an extensive upgrade effort encompassing all F-35 variants. The Block 4 program has been plagued by cost growth and schedule delays, raising concerns about the timeline for introducing its key enhancements.

“F-35 Lightning II aircraft are being built to accommodate the F-35 advanced radar (APG-85) for [the] US Air Force, Navy, and Marine Corps,” a spokesperson for the F-35 Joint Program Office told TWZ in response to inquiries prompted by the Defense Daily report. “Initial fielding for some F-35 aircraft is planned for Lot 17, which began delivery in 2025 and continues through September 2026.”

The spokesperson added: “Due to program security reasons, we are protecting any additional information with enhanced security measures.”

Lockheed Martin, the prime contractor for the F-35 program, referred inquiries back to the JPO. Northrop Grumman, which is developing the APG-85 radar, also declined to comment.

Although specific technical details about the APG-85 remain limited, the radar is known to be an active electronically scanned array (AESA) system, similar in architecture to its predecessor, the AN/APG-81. It is expected to incorporate air-to-air and air-to-ground modes, as well as synthetic aperture radar (SAR) mapping capabilities, enabling the production of high-resolution imagery for target acquisition, identification, and reconnaissance.

Low probability of intercept/low probability of detection (LPI/LPD) features are also anticipated to be integral to the APG-85’s design. When paired with the F-35’s stealth characteristics, such features would reduce the likelihood of detection and electronic countermeasures. Radar emissions themselves can provide adversaries with a means to detect and track stealth aircraft, underscoring the importance of minimizing signature exposure.

As with the APG-81, the APG-85 is expected to be tightly integrated with the F-35’s electronic warfare suite and broader sensor architecture. A new electronic warfare package is also reportedly in development for the Joint Strike Fighter, further expanding the aircraft’s capabilities.

Beyond architectural refinements, the APG-85 is poised to benefit from decades of technological advancement. In particular, the adoption of gallium nitride (GaN) technology has significantly improved modern radar systems in terms of size, weight, power efficiency, and overall performance. By contrast, the APG-81 traces its origins to development efforts that began in the 1990s.

While direct confirmation remains elusive, the cumulative weight of available information provides substantial circumstantial evidence. The JPO has acknowledged that F-35s “are being built to accommodate” the APG-85 and that Lot 17 aircraft—delivered beginning in 2025—are intended to be the first to field the new radar. At the same time, the APG-85 remains under development, raising questions about the configuration of currently delivered aircraft.

By Vafa Guliyeva