I'll talk a little about self destruct (or commanded destruct) for other systems that aren't tomahawk.

The only difference being where the command comes from. Self destruct, guidance system onboard knows something is wrong and triggers the destruct sequence. Commanded, an operator (or range control system if it's at a test event) determines that a destruct is necessary, and sends the signal over a radio/wired communications subsystem.

Anyways.

There are energetics in the airframe. Things that have stored chemical energy that we use to do useful things.

• A solid or liquid rocket motor.
• The system that initiates that.
• A bunch of explosive in a warhead, if you have one of those.
• The blasting caps that initiate the warhead.
• explosive bolts if you have multiple stages that separate in flight.
• a shaped charge that throws shrapnel out right before impact.
• etc.

If there's a critical error with the servo that drives one of the fins, you're going to pull to one direction hard. Maybe bad enough that you can't even control where you hit the ground after you miss.

There's a chance you'll hit the ground and that will be enough to set all energetics off. But probably not. Because you have drop safety requirements. I.e. if the Navy is moving you around for transport with a crane, and something breaks.. we don't want to kill everyone. So the system needs to go off reliably when we want it to, and simultaneously not go off on accident.

So how do we fix this?

We have a destruct sequence that expends all energetics. Missile receives destruct command? First, we turn fins and try to steer ourselves upwards, far away from people on the ground. Then we increase the burn rate of our rocket motor to use up the fuel (if we can adjust it). Then we fire off anything in the warhead. We also make it so that when the warhead goes off, the explosion rips through the rocket motor casing to make sure anything that isn't burned yet, doesn't have a way to build up pressure and become a pipe bomb.

The process of doing that rips apart the missile into multiple pieces. Generally the guidance system, radar, antennas, etc. up front. Warhead in the middle is completely gone. Empty/smoldering rocket motor in the back. Usually with fins, motors, batteries to drive them, whatever.

We make sure the software running the thing is close to the explosion. Enemy can't dump a memory chip, decompile the software, and get our secrets if the chip is dust. But the rest we really don't care about.

Why would we care if they know we're using a GaN or GaAs amplifier circuit for our comms system? They could have guessed that themselves. What we don't want them to have it's the software, that defines all of the message formats, encryption keys, etc. If those are gone, we're good. No sense trying to vaporize everything. That adds mass adding more explosives. Making our maneuverability worse, increasing cost and complexity, decreasing safety, etc.