(Bloomberg) -- Lockheed Martin Corp.’s F-35, the world’s costliest weapons system, may fail to keep pace with Chinese and Russian air defense improvements given its “extraordinary costs” so far, the U.S. House defense policy committee has warned.

The House Armed Services Committee supported the F-35’s $398 billion acquisition program in the report accompanying its version of the fiscal 2022 defense policy bill. It said the sophisticated fighter “can be used against advanced integrated air defense systems operating against the United States or its foreign partners and allies during high-end, very contested contingencies” once it finally receives key software upgrades.

But the committee called into question “overly aggressive development and production schedules” that for more than 20 years have resulted “in longer schedules and much higher costs than planned to realize less than full warfighting capabilities required by the Department of Defense.”

With adversaries that pose “near-peer” challenges advancing more rapidly than expected, the panel said it’s “uncertain as to whether or not the F-35 aircraft can sufficiently evolve to meet the future expected threat in certain geographical areas of operations in which combat operations could occur.” 

The committee didn’t name the adversaries of concern but Pentagon officials cite China as the prime threat driving U.S. defense investments and also note Russian moves.

The panel’s view reflects that the F-35 still hasn’t demonstrated its capabilities in a simulation against the most challenging Russian and Chinese air defense systems. The exercise to be run by the Navy was most recently supposed to have been completed in December, though it was originally planned for 2017. 

In April, Bloomberg News reported that the Defense Department’s F-35 program office projected the target date as August 2022. The Pentagon has not provided an official date since then.

The Pentagon requested 85 F-35s for the fiscal year that begins Oct. 1, up from 79 this year. The House Armed Services panel cut five, authorizing 80s. The Senate Armed Services Committee added six jets. The House Appropriations Committee approved 85; its Senate counterpart hasn’t acted on its bill yet. More than 690 F-35s of more than 3,000 projected have been delivered and are operating from 21 bases around the world.

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