The Pentagon’s premier F-35 fighter jet program has fallen below mission-ready standards for six years, a government watchdog said on Monday.

The F-35 often costs close to $100 million per unit, and the Pentagon expects to spend roughly $2 trillion on the program over the coming decades. But even as one of the Pentagon’s most expensive weapons, all variations of the fighter jet have missed their mission-capable rate goal since fiscal year 2018, according to a Government Accountability Office (GAO) report released Monday.

Mission capable rate goals are defined as “the percentage of total time when the aircraft can fly and perform at least one mission,” and are used to gauge the readiness of various military assets, according to the GAO report. There’s a variety of factors contributing to the F-35’s lackluster performance, many of which have been publicly reported, but the Pentagon still hasn’t taken some of the proper steps needed to address the problems.

“In September 2023, we reported that several maintenance challenges negatively affected F-35 readiness and the ability of the aircraft to achieve mission-capable goals,” the report reads.

Part of the problem stems from a lack of needed parts, lengthy maintenance backlogs and “challenges with depot and organizational maintenance,” according to the report. The Pentagon also heavily relies on defense contractors for the F-35 program — even though it doesn’t want to — but hasn’t taken any steps to try and take back control of the program. (Read more from “Pentagon’s Trillion Dollar Fighter Jet Program Hasn’t Had Mission-Ready Plane in Six Years, Watchdog Says” HERE)