Lockheed Martin’s F-34 fighter production line.

 

WASHINGTON — The Pentagon’s most expensive weapons program is once again behind schedule and light on details. A new government watchdog report says Lockheed Martin’s long-delayed upgrades to the F-35 fighter jet—known as Block 4—have been scaled back, slowed down, and may still be years from completion.

And the kicker? No one knows exactly what’s included or how much it’ll cost.

The Government Accountability Office (GAO) dropped its latest audit of the Joint Strike Fighter on Tuesday, bluntly titled: “Actions Needed to Address Late Deliveries and Improve Future Development.” In it, they paint a familiar picture: big promises, shifting timelines, and a contractor getting paid despite falling short.

Originally pitched as a major leap forward, Block 4 was meant to give the F-35 new weapons, better radar, improved communications, and smarter targeting software. Think of it as the fighter jet’s mid-life makeover—bringing it up to speed against evolving threats.

At one point, the upgrade included more than 80 different improvements. That list is now down to “a subset” of 66, the report says, but officials aren’t saying which ones survived the cut.

Some upgrades were dropped because they no longer “meet warfighter needs.” Others are on hold until the engine gets its own overhaul—now expected in 2033.

Before Block 4 can even function, the jet needs a hardware boost called Technology Refresh 3 (TR-3). That’s the brainpower behind the new features—faster processors, updated software, and more memory.

But testing for TR-3 has been delayed for over a year, grounding new F-35 deliveries. In 2024, jets and engines were arriving an average of 238 days late. The GAO calls this a red flag—and a sign of deeper trouble in Lockheed’s supply chain and production lines.

The report says Lockheed Martin plans to deliver the upgraded, combat-ready jets in 2026. That’s three years later than originally promised.

In short: the system designed to enable the upgrades is late, so the upgrades themselves are even later.

To make it easier to track what’s actually happening, Congress ordered Block 4 to be treated as its own sub-program in 2023. Until now, it was buried in the F-35’s $2 trillion price tag—making it hard to isolate cost overruns or delays.

That transparency is badly needed. GAO says the Pentagon won’t even know the new price tag for Block 4 until this fall. And until that’s done, no one can say with confidence what the final version of the upgrade will actually include.

One of the sharpest jabs in the report: Lockheed and its engine partner, Pratt & Whitney, are still getting paid bonuses—even when deliveries are late.

GAO flatly recommends changing that system. “Don’t reward delay,” the report says in so many words. Instead, align incentives with actual performance. Deliver on time, or don’t get paid extra.

Other GAO recommendations include:

  • Evaluating whether Lockheed can even meet current production goals.

  • Expanding the use of digital design and testing tools.

  • Matching production goals to actual contractor capacity.

The Pentagon agreed with most of the recommendations. But the watchdog agency said more action is needed.

GAO isn’t throwing out the whole program. They call the F-35 “critical to our national defense and that of our allies” and acknowledge the jet is finally shifting out of R&D and into real-world production. But after 20 years of overruns and underperformance, they say now is the time to enforce accountability.

A finalized contract for the next batch of F-35s—Lots 18 and 19—is expected “at the start of autumn,” according to a Pentagon spokesperson. That handshake deal was reached nearly a year ago, and the public still doesn’t know what each jet will cost.

Until then, it’s more waiting, fewer features, and no firm answers. For a jet that was supposed to be the future of air power, that’s not a great look.