> But how capable would those reservist truly be?
It's been said repeatedly by many NK escapees that the supply of ammunition is strictly controlled because the first bullets fired by any conscripts in the event of any hostility would most likely be through the heads of the officers commanding the conscripts.
Same applies to all those weapons dug in facing South. Unless concreted in position they can easily be turned around - and I assume they're all pretty well pinpointed targets to the point where they'd be lucky to get one shot off anyway.
In the event of open warfare the most difficult thing that would be encountered is likely to be tens of thousands of NK soldiers clamouring to surrender (It is a lot harder to deal with than it sounds, as the USA found out during GW1).
At this point in proceedings, support and alliances may come from unlikely sources. NK is the world's largest source of methampetamines and can probably call on assistance from drug cartels and other criminal orgs if it needs to. The battlefields are likely to be everywhere in such an event.