There are 8 million lines of code in the F35 integrated computer system.
So, how the hell would anyone know one way or the other? Only Israel is permitted extensive independent testing and access to open custom design. All other countries must test systems on the US continent and have US oversight during testing.
"You see, there is no kill switch, but you do have to install this software license that expires every tree months. That's so we know you paid for the required service updates and software support."
"But if you don't give a license, the plane doesn't fly!"
"Well, yes, but we can't shut it down remotely so it's technically not a kill switch."