The US Air Force (USAF) has refused to either confirm or deny reports that the new lot of F-35 Lightning II fighter jets is being delivered without radars.
The F-35 fighters were supposed to start arriving with state-of-the-art AN/APG-85 radars, a critical component of the larger Block 4 upgrade package, from 2025. All the previous lots of the F-35 jets were equipped with the AN/APG-81 radars.
However, due to delays and technical issues with the AN/APG-85 radars, the F-35 fighter jets were reportedly delivered to the US military without them.
While there is no official confirmation from the USAF, Lockheed Martin (the primary contractor for the F-35 Joint Strike Fighter (JSF) program), or Northrop Grumman, which is developing the APG-85 radar, there is substantial circumstantial evidence suggesting it is indeed the case.
In fact, according to reports, since June last year, Lockheed Martin has been delivering F-35 fighter jets to the US military with ballast rather than radars.
It is not clear when or who made the decision to accept the aircraft without radar. Nor is it clear how many F-35s have been delivered without radars. In 2025, Lockheed Martin delivered a record 191 F-35 jets, including to the US military and foreign clients.
However, radar-less F-35s were delivered only to the US military, as foreign customers are still currently acquiring jets fitted with the older AN/APG-81 radar.
The new AN/APG-85 radar requires completely different mounting systems on the F-35 jets than the older AN/APG-81 radar.
According to Defense Daily, since June 2025, new F-35s have been supplied with updated mounting systems, which is why they lack radars altogether.
At the same time, additional ballast is installed in the nose section to maintain balance.
These jets will be retrofitted with the new AN/APG-85 radars at a later stage.
AN/APG-85: The GaN Leap
Details about the capabilities of the new AN/APG-85 radar are extremely limited. However, like its predecessor, the AN/APG-81 radar, it is expected to be an active electronically scanned array (AESA) radar with air-to-air and air-to-ground modes.
Similarly, like its predecessor, the APG-85 is expected to have synthetic aperture radar (SAR) mapping capability, allowing it to generate high-resolution images.
However, while the AN/APG-81 radar uses gallium arsenide (GaAs) TR modules, the AN/APG-85 radar will be based on a gallium nitride (GaN) architecture to deliver higher power density, improved thermal efficiency, and extended detection envelopes in contested electromagnetic environments.
As is the case with GaN-based radars, the APG-85 demands more power, approximately 82 kilowatts, which is substantially higher than earlier configurations, necessitating new structural, cooling, and energy-distribution requirements on the F-35’s forward fuselage and internal systems architecture.
Thus, the installation of the new AN/APG-85 radar on the F-35 is also linked to the aircraft’s engine upgradation project, another key component of the Block 4 upgradation project.
An engine upgrade program, the Engine Core Upgrade (ECU) initiative for Pratt & Whitney’s F-135 engine, is currently underway for at least some variants of the F-35 but is also running behind schedule.
“The arrays on it [the APG-85] give it much more power, which is why we have to upgrade the engine,” Rep. Rob Wittman, currently Vice Chairman of the House Armed Services Committee and Chairman of its Tactical Air and Land Forces Subcommittee, told Defense Daily last week in an interview. “I think we need about 82 kilowatts of power versus what it’s producing right now.”
The AN/APG-85 radar was supposed to be integrated with Lot 17 jets; however, this has been pushed to Lot 20.
Can Radar-Less F-35s Be Used In Combat Situations?
The AN/APG-85 radar was designed to enhance long-range detection against low-observable adversary aircraft, such as China’s J-20 and Russia’s Su-57.
However, a source told Defense Daily that radar-less F-35s can still function and fly as a fully operational aircraft.
“Radar-less F-35s have been able to fly, as long as they are accompanied by other F-35s, data-linked and equipped with the APG-81.”
Since the F-35s are equipped with extensive infrastructure for information exchange, as long as these radar-less F-35s are flying with other radar-equipped F-35s, they can exchange the battlefield picture via their Multifunction Advanced Data Links (MADL).
Theoretically, these jets could still be sent into combat, at least in an emergency; however, this would definitely entail exposing them to greater risk, as the radar-equipped F-35s would have to rely more on their radars, which could be a vulnerability.
Overall, the F-35 JSF program has a long history of accepting jets without key features, which were installed later as their technology matured.
Now, the same thing is happening with Block 4 upgrades, which involve integrating more than 80 enhancements, including expanded electronic warfare suites and 66 additional weapon integrations.
Initially, all 66 capabilities under Block 4 were scheduled to be fully deployed by 2026. This timeline was later pushed to 2029.
In September last year, the Government Accountability Office (GAO), a Congressional watchdog, published a report stating that even after reducing the scope of Block 4 F-35 upgrades, Lockheed Martin will still need two years to develop and install the planned improvements.
The report also said that the Block 4 effort’s price tag had risen by US$6 billion.
The report also warned that Lockheed Martin will not be able to deliver the Block 4 upgrade, even with only a “subset of the original 66 … capabilities,” by 2031, five years later than the initial timeline.
Apart from the APG-85 radar, the Block 4 updates also include replacements for the jet’s existing AN/AAQ-37 Distributed Aperture System (DAS), Electro-Optical Targeting System (EOTS), data-sharing, navigation system, powerplant, computer processing, electronic warfare package, and thermal cooling capabilities.
When the APG-85 radar will be ready for installation on the F-35 remains to be seen. However, the APG-85 radar is just one aspect of the many challenges ailing the Block 4 updates, which are also struggling with chronic cost overruns and repeated delays.
- Sumit Ahlawat has over a decade of experience in news media. He has worked with Press Trust of India, Times Now, Zee News, Economic Times, and Microsoft News. He holds a Master’s Degree in International Media and Modern History from the University of Sheffield, UK.
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