Why not remove PAL* and delegate authority to local commanders? I'd rather take the risk of trusting a human over a human designed, highly complex computer system.
In the UK, due to the lack of land-mass to absorb a strike, the PM issues final orders to the commanders of the Trident subs. This is part of the deterrence strategy.
* https://en.wikipedia.org/wiki/Permissive_Action_Link https://en.wikipedia.org/wiki/Letters_of_last_resort