Comment by hollerith
Actually, I trust Apple's hardware security enough that I think it is probably impossible for anyone in China (even though they have physical access to the devices) to alter an iPhone or Macbook so that its own electronics can be used to trigger any explosive the attacker might install in the device, so in addition to an explosive, the attacker would need to install his own radio receiver. And the attacker probably won't be able to use the device's electronics to eavesdrop on the device's user, so no ability to tell whether the user is in the group the attacker wants to target unless again the attacker installs his own electronics (including radio transmitter) to do the eavesdropping.
> it is probably impossible for anyone in China (even though they have physical access to the devices) to alter an iPhone or Macbook so that its own electronics can be used to trigger any explosive the attacker might install in the device
It would be trivial for a Mossad-level adversary to get around this. The pager explosives were disguised inside the battery, not around it. If you replaced the iPhone's 4500mAh battery with a 3500mAh one containing RDX and a 3G radio, you'd have to be mega-paranoid before you noticed the difference.
This is exactly the sort of hubris modern intelligence agencies rely on in order to exploit your misplaced trust. Apple's hardware security, much like their software security, is mostly predicated on marketing and not the transparent or accountable defense of your device.