At my first Help desk job we decommissioned hard drives by taking them to the range and shooting them with my boss's aircraft gun converted into a rifle (he was a former Air Force plane mechanic and kept a decommissioned barrel)

My current job is lame since we just stick them in a degausser.

I had thermite grenades for our radar when i was in Iraq. In the event of capture we were supposed to put a grenade on the computer parts, anything with cryptography, and the radar.

Thermite is much easier to destroy stuff than a bullet or 30.

The GRID Compass, arguably the first laptop, had a magnesium case. When three-letter agencies bought some for field use, they drew an X over the nonvolatile storage.

It was so that if the downed plane got captured by other forces, they would have less working parts to reverse engineer the function from, not because people were worried about rogue autopilots they couldn't shut off.

When I was in school, a classmate had done a coop for the Canadian military. They used the ADA programming language (iirc), and it was such a safe language that the only unrecoverable exception they allowed in their programs (for a military helicopter) was one where the user had selected the self-destruction option and the exception was so that the program could switch from "flying the helicopter and running its systems" mode to "scramble the memory to minimize the useful data that might be recovered from it" mode.

Presumably trying to keep the microprocessor tech out of Soviet hands.

Trust but verify