Well, if they see one lone cruise missile, I doubt they will jump for launching nukes in peace time... Even if they were to, missile like Brahmos might hit before they can even open the silo hatch or erect the TEL. I will be more worried about air traffic though. They can shoot down an airline in hurry.
Yep I agree....if they detect, they see its one and (assuming no hotline msg arrived) will wait to see what that is.
If they dont detect (say ground hug sneak attack and no aerial assets on their end airborne looking at that particuar sector, which is very likely)...then the whole thing is redundant as they only have the after-effect to respond to.
But in larger analysis above this kind of thing:
In worst case salvo situation (for them), even then its not hair trigger stuff at all.....as keeping stuff on hair trigger makes it magnitudes more detectable and vulnerable to a first strike.
If you want survivability and deterrence of own warheads....they need to be kept de-mated and off hair trigger status as far as possible.
i.e components stored separately (with relevant organisation of decoys etc as well) like the bean and eggshell game made larger to hedge the most against the opponents detection capability and probability analysis.
Simply put Pakistan does not have the strategic depth or warhead stockpile that US or Russia have. (In fact no country does outside those 2).
Those are the only two countries that can afford to keep land based systems on some level of hair trigger, mostly precipitated by those (apparently ~ 1k on each side) warheads exposure and vulnerability to begin with...and the inertia from cold war of having these to begin with.
....i.e a use or lose equation concerning those specific warheads, thus largely they are tasked with non-strategic targets (mostly tasked with counterforce on the likely opponent stockpiles) as well.
Changing this equation somewhat (from a status quo) was largely basis of one pressure lever the US elected for under Reagan in the 80s...in Europe...that the US earlier denied itself under larger detente reached post-SALT.
But it was a full strategic decision, rather than response to any more relative fly swat incident.