It's an inference. The author is saying that because the Air Force is pursuing a new plane with the same fundamental goals that launched the F-35 program, then the F-35 evidently failed to deliver. He's saying they're really just asking for a do-over.
> Instead of ordering fresh F-16s, he said, the Air Force should initiate a “clean-sheet design” for a new low-end fighter. Brown’s comments are a tacit admission that the F-35 has failed.
(Emphasis mine. Tacit means "implied without being stated".)
> Instead of ordering fresh F-16s, he said, the Air Force should initiate a “clean-sheet design” for a new low-end fighter. Brown’s comments are a tacit admission that the F-35 has failed.
(Emphasis mine. Tacit means "implied without being stated".)