How do they expect provoking NK to end?

[EX500rider]

39. Downtown Seoul is 26 miles from the closest border point...

......no mortars have that range. Most of N Korean artillery doesn't have that range.
A small portion of their artillery could reach, not enough to kill everybody in the city though.

Here'a more realistic assessment:


The North Korean military's most powerful tool is artillery. It cannot level Seoul as some reports have claimed, but it could do significant damage. Pyongyang risks deteriorating its forces by exposing them to return fire, however, which significantly restricts their use. Less conventional methods of retaliation, such as sabotage or cyber warfare, are less risky but also limit the shock that North Korea would desire.
After a strike, North Korea's most immediate and expected method of retaliation would center around conventional artillery. Many of the North's indirect fire systems are already located on or near the border with South Korea. By virtue of proximity and simplicity, these systems have a lower preparatory and response times than air assets, larger ballistic missiles or naval assets. Nevertheless, there are several critical limitations to their effectiveness.

The biggest anticipated cost of a North Korean artillery barrage in response to an attack would be the at least partial destruction of Seoul. But the volume of fire that the North can direct against the South Korean capital is limited by some important factors. Of the vast artillery force deployed by the North along the border, only a small portion — Koksan 170-mm self-propelled guns, as well as 240-mm and 300-mm multiple launch rocket systems — are capable of actually reaching Seoul. Broadly speaking, the bulk of Pyongyang's artillery can reach only into the northern border area of South Korea or the northern outskirts of Seoul. All forms of North Korean artillery have problems with volume and effectiveness of fire, but those issues are often more pronounced for the longer-range systems. Problems include the high malfunction rate of indigenous ammunition, poorly trained artillery crews, and a reluctance to expend critical artillery assets by exposing their positions.
Based on the few artillery skirmishes that have occurred, roughly 25 percent of North Korean shells and rockets fail to detonate on target. Even allowing for improvements and assuming a massive counterstrike artillery volley would be more successful, a failure rate as high as 15 percent would take a significant bite out of the actual explosive power on target. The rate of fire and accuracy of North Korean artillery systems is also expected to be subpar. This belief is founded on the observably poor performance of North Korean artillery crews during past skirmishes and exercises. Though inaccuracy is less noticeable in a tactical sense — especially as part of a "countervalue attack," where civilian areas are targeted — at the higher level an artillery retaliation rapidly becomes a numbers game.

Ineffective crews also rapidly curtail the potential for severe damage. Rate of fire is crucial to the survivability of artillery systems — the name of the game is to get the most rounds on target in the shortest period of time, lest your position be identified and destroyed before the fire mission is complete. Poor training translates to a greatly reduced volume of fire and a painfully limited duration of effectiveness.

https://www.stratfor.com/analysis/how-north-korea-would-retaliate