[bhhaskin]

Nukes are a different beast entirely. Quite a few of their safety systems are physical and non-networked. The only danger are hacking delivery systems such as subs and bombers. But that would only prevent the delivery of a nuke, and not set them off.

[siffland]

As i recall it takes 2 people to physically launch an ICBM from either a bunker or a sub (simultaneous key turns). The other delivery method is a bomber, not sure what is takes to arm those.

[cameldrv]

ICBMs can also be launched through the Airborne Launch Control System, which sends a radio signal from an aircraft to the silo. ALCS commands have a delay and a time window of a couple of minutes I believe where they can be reversed by the crews in the LCCs, but absent their intervention, nuclear missiles can be hacked.

[bhhaskin]

I am pretty sure it still requires the silo crew to launch the missile. Or at the very least have the missiles be in some kind of alert ready status.

* Update: Never mind, I stand corrected. You are correct. https://en.wikipedia.org/wiki/Airborne_Launch_Control_System...

[cameldrv]

This is a pretty interesting document, and gives quite a few hints about the workings of the ALCS: https://static.e-publishing.af.mil/production/1/af_se/public...

My understanding is that inside the capsule LCCs, if the ALCS sends a launch order, if they do nothing in two minutes, the missile launches. I believe any of the ten LCCs in the wing can abort the launch. Then there's some arbitration procedure where another LCC can reverse this and decide to launch after all, and then I think the wing commander's LCC can have a final override on that. The intention is that if all of the LCCs are destroyed, the missiles can still be launched, since there would be no one left to abort the launch, but under normal conditions, the ALCS would not be able to launch. The government is currently starting to build a new ALCS replacement system that is IP based, which I think has to be about the worst idea I've ever heard of.