I think that in order to understand what's going on between North and South Korea, and I mean REALLY understand it, you must have spent time in Korea. There is a national flavor to the situation that I haven't found anywhere else on the planet. Much of it has to do with emotion and pride that runs to the very core of the culture -- going back thousands of years. The only way I have found to explain it to make it meaningful to people in "the West" is to explain it this way: When Gene Roddenberry (created of the popular media series, Star Trek) wrote about Klingons, he used Koreans as the model.
That is not to say that I don't like Korean people. Quite the opposite. It's just that trying to explain a Confucian warrior culture to somebody who hasn't been exposed to it is difficult.
On 20 August, North and South Korea carried out their respective threats. North Korea threatened to destroy South Korean propaganda broadcast stations. At 15:53 local, it fired a single round at a broadcast station in Yeoncheon, Gyeonggi Province. At 16:12 it fired a greater number of shells across the Demilitarized Zone. South Korean authorities said the attack caused no casualties or serious property damage.
Senior South Korean authorities threatened strong retaliation for any North Korean provocations and authorized forward forces to retaliate. In response to the North Korean fire, South Korean 155-mm howitzers returned fire. North Korean media said they fired 36 shells, but inflicted no casualties.
The South Korean national defense ministry said that about 17:00 local time, it received a message from North Korea via a communications link at Panmunjom that contained an ultimatum from the General Staff of the Korean People’s Army. The ultimatum said that if the South did not stop the propaganda broadcasts within 48 hours from 17:00, then the North would begin strong military action.
A South Korean military source said Wednesday that North Korea’s military was ratcheting up its combat readiness posture. Front-line fortifications have opened their weapons portholes and units had intensified artillery firing drills. “The North Korean army is performing its exercises more frequently, including one that aims to speed up artillery operations.”
Later on the 20th, North Korean media reported that Dear Leader Kim Jong Un ordered the Korean People’s Army to move to “semi- war” combat readiness as of 17:00 Korea time (0430 ET) on 21 August.
South Korean forces are at their highest alert level. South Korea has implemented a partial evacuation of civilians from the western part of the Demilitarized zone.
The semi-war combat readiness condition is the second highest combat readiness condition. A semi-war state brings the combat forces to a condition from which they can launch attacks without warning, although all readiness measures are not completed. It always means there is a crisis, but not that a general war is imminent or likely.
The North appears ready to order increased readiness to the civilian sector, but the report does not indicate that Kim gave such an order. The changes to civilian normality under an order to increase civil readiness are so disruptive and destructive of national life that they would mean the end of Kim’s building and development programs for a considerable time. Such an order to the civil sector also would significantly increase the probability of an armed confrontation across the Demilitarized Zone.
Conditions are in place for a potentially serious escalation. The North Korean ultimatum requires some form of military action against the South Korean broadcast stations to prevent a loss of face. The North Koreans might have misjudged South Korea’s readiness and willingness to take them on. The chances of a miscalculation of intentions feeding escalation of the crisis are high. It's likely that North Korea will test a ballistic missile by shooting it in the general direction of South Korea.