F-35. American built, Russian inspired...never proven.

Yak 141.

The world's first Supersonic STOVL airplane.  Do you recognize the engine layout?  Basically the same as the F-35.  This airplane never went into production.

What does all this have to do with the price of tea in China?  It boils down to the fact that (and I hate having to admit this) STOVL capability and the airplanes that the USAF and USN need are totally incompatible.  You can share avionics, engine cores etc...but sharing airframes is a step too far.

The F-35.  American built, Russian inspired, never proven and an eventual failure.  How do we know?  Because even the daddy's of this design (the Russians) abandoned it.