The Pentagon is blocking release of a June Government Accountability Office report on the F-35 Joint Strike Fighter program, indicating that the report contains “Controlled Unclassified Information.” CUI is designation used by federal officials to characterize information created or possessed by the government that requires safeguarding or limited public access.

No details about the specific CUI have been offered by the Pentagon. The unreleased, June 25 report is titled, “F-35 Joint Strike Fighter: Update on Production and Modernization Efforts.”

The F-35 is a series of single-engine, Stealth-enabled aircraft deployed for ground attack and combat, and available in three variants. The jets have been in production for more than a decade, and currently the more than 1,300 completed aircraft are being updated and enhanced with new combat capabilities, including electronic hardware and software advances to facilitate dozens of new weapons systems.

Lead contractor Lockheed Martin is currently in production with Lot 20 of the F-35 program, which will include 65 aircraft of all three variants - F-35A, F-35B, and F-35C.

However, program costs difficult to establish. It was not until September 2025 that the Pentagon and Lockheed settled a $24.3-billion contract for 296 aircraft in Lots 18 and 19, with those aircraft already in production. A year earlier the two sides had negotiated a framework agreement on production costs, generally fixing the unit price at $82.4 million per aircraft.

In December 2025 the Pentagon’s own inspector general reported that the F-35 Joint Program Office has not consistently held the lead contractor Lockheed Martin accountable for poor performance in sustainment activities for the fighter aircraft. It established that the F-35 jets had achieved a readiness rate of just 50%, though the contractor was paid in full without any fees or adjustments.

The GAO is an independent agency that for more than 20 years has been under Congressional mandate to prepare an annual report on the F-35 program. Cost-overruns, production delays, maintenance costs, and aircraft readiness have been the major issues raised by critics of the program, and guiding the annual GAO report.

Earlier in June GAO issued “F-35 Sustainment: Actions Needed to Ensure Updated Strategy Improves Persistent Readiness Challenges,” in which it reported:

“F-35 sustainment costs have continued to increase, but the F-35 has not met performance goals and performance has trended down. Across the fleet from fiscal year 2021 through fiscal year 2025:

• The mission capable rate (percentage of time the aircraft can perform one of its tasked missions) declined from 67 percent to 44 percent.
• The full mission capable rate (percentage of time the aircraft can perform all of its missions) declined from 38 percent to 25 percent.”