If you have physical possession of a nuclear warhead & the necessary engineering skills, it should be possible to remove the control circuitry & fit your own, with whatever launch codes you want.
Think of it like a car key. If you have the car, a properly equipped workshop & the right skills, you can remove the locks & fit other locks. You can then drive the car.
It's not a trivial thing, but given the resources of a modern industrial state it is far from being an insuperable problem.
Think of it like a car key. If you have the car, a properly equipped workshop & the right skills, you can remove the locks & fit other locks. You can then drive the car.
It's not a trivial thing, but given the resources of a modern industrial state it is far from being an insuperable problem.