To be, not to be is the biggest tragedy of human history. as written by Shakespeare.
Nowadays every new electronic system is based on hardware and software. The previous electronic systems were only based on only hardware to perform its requisite functions. With the advent of software, electronic systems are more intelligent and efficient to do their intended functions.
The question of some hidden coding in an electronic product is absolutely possible, and I have come across many situations where we need such codes to perform operations that are not intended and designed for users or customers. such hidden functions are intended for OEM admins to perform configurations of the systems. The user can only avail of the options intended for him. He has access only to the operational domain of the system, anything beyond is strictly kept hidden and secret well protected.
Everyone knows about remote control and monitoring. remote programming is a daily norm.you can access software-based systems from anywhere in the world. we see such examples of software update of computers and smartphones. Why the USA is opposing Huawei telecom systems? Americans can not use it for its secretive purposes? why? coding is with a Chinese firm. only the OEM has a right to complete access.
Now is there any such domain of systems that is not available to Pakistan as an end-user of F-16? There should be many systems and subsystems that must be kept secret from Pakistan or any other end-user. these hidden functions remain hidden for the product's entire lifespan.
Can the USA add such code or piece of hardware to F16? sure, it is absolutely possible. We should learn about the USA what it had been doing in the Past? If it has a reputation of doing such things, surely it must have done similar in F-16. If the case is the opposite we should relax and praise the naivety of the USA. whatever we think the possibility it is up to us.
The simplest example of this toner cartridge of a printer. even after filling the cartridge, you can not use it, The manufacturer of the printers wants the users to purchase a new toner cartridge. for it has a chip inside. You will need a software engineer and programmer to reprogram or replace the chip and refill the cartridge.
Kill switch means some hidden or not known way of access to that product making it useless. OEM has full access to the coding so he can do whatever he wants in the world with his products. He will never reveal his secrets to anyone else. These secrets maybe a piece of software or hardware intentionally added to that product for a specific purpose. sometimes we call it master code or master key. The end-user can not be smart enough to know the unrevealed secrets of any product completely. OEM does his best to safeguard and protect his IP.from reverse engineers, hackers, and crackers.
IMO, new systems offer endless options to the manufacturer to do whatever he intends to do with his product, the End user is always at the mercy of the Makers. It would be naive to think them stupid. the makers are the most intelligent and smart people. these over smart can easily befool the users.
this is an opinion of a system designer, not an end-user.