Group 1 - The U.S. Air Force has received some F-35A fighter jets without radar installations since June 2025, attributed to delays and cost overruns in the AN/APG-85 radar development [1][3] - The F-35 Joint Program Office (JPO) has not confirmed or denied the situation but stated that the integration of the APG-85 radar is planned to begin with the 17th batch of aircraft, continuing until September 2026 [3][4] - The installation of the APG-85 radar requires physical modifications to the F-35's airframe, and there is currently no universal mounting structure compatible with both the existing APG-81 and the new APG-85 radar [3][4] Group 2 - Lockheed Martin has proposed redesigning the F-35's airframe to accommodate either radar type, with the new configuration expected to be implemented in the 20th batch around 2027-2028 [4] - F-35s without radar are limited to flying only with radar-equipped aircraft for training, which significantly restricts tactical flexibility and increases detection risks [4][5] - The F-35 program has faced ongoing issues with "concurrent production," leading to complex retrofitting and high maintenance costs, which continue to affect the project [4][5] Group 3 - The F-35's capabilities are notably diminished without radar, as it cannot independently perform missions in high-threat environments and lacks essential electronic warfare functionalities [5] - The overall progress of the F-35 Block 4 upgrade is concerning, with a reported $6 billion cost overrun and a delay of at least five years [5] - Additional challenges include issues with the F135 engine's power and cooling capabilities, further hindering the upgrade process [5]