Our F-35s cannot even be Seen By Our Own SAM Batteries?

I guess warplanes are now much better than the defenses nowadays.

The F-35 has hit yet another snag. During a recent exercise at Mountain Home Air Force Base in Idaho, US Air Force F-35A pilots set out to practice evading surface-to-air missiles, but they could not, because the SAM radars on the ground could not even find the ultra-stealthy planes.

"If they never saw us, they couldn't target us," said Lt. Col. George Watkins, commander of the 34th Fighter Squadron at Hill Air Force Base, Utah, told the Air Force Times.

To participate in the exercise as planned, the F-35As had to turn on their transponders, essentially announcing their presence so the SAM sites could see and engage them. 

So they had to turn on the "shoot-me" sign or they would have never even got the missiles to lock on? I would hate to be any other country right now. We can essentially fly in and evade any SAMs and then fly out without them even knowing. I guess death by totally stealthy warplane might be yet another way for us to kill ISIS terrorists.