Re: Israel F35
"Stealthy" doesn't mean "cloaked". Maybe the reflectors would change the radar signature so that the Russian-supplied air defence systems can't get all calibrated and ready for it in its natural state. You know, a bit like when a newly-designed car goes out for road-test and they paint it with patterns to disguise the shape. Or perhaps it deploys the reflectors when it's in friendly airspace to stop commercial aircraft bumping into it all the time.