Seoul, the capitol of South Korea, is within range of the North Korean "Korean People’s Army" (KPA) artillery, specifically the 620 Artillery Corps and the Kangdong Artillery Corps. Each corps possesses 6-12 brigades, each with 35-70 guns. Thus the KPA has approximately 1200 pieces pointing at Seoul. These weapons range from 155mm heavy guns to 240mm rocket launchers.
This is true, but it is also wrong to say that it means South Korea cannot respond militarily. The article accepts that South Korea must do more, so clearly South Korea can't make passivity in the face of repeated--if occasional--attacks by the north their policy. That would be very demoralizing for South Korea's military and people.
I've advocated keeping the response at sea to make sure that escalation to the land DMZ is something North Korea must contemplate. For however much a war could devastate Seoul (where a quarter of South Korea's population lives), a war could destroy the North Korean regime. Fear isn't just something South Koreans have to feel. So quietly destroy some North Korean military asset at sea and do what North Korea has done--deny it.
Or if that seems too risky for South Korea's leaders, draw up plans to deal with the next clash at sea with North Korea. Instead of damping down any clash quickly, make sure that South Korean assets destroy any North Korean vessels that are in the clash. Pursue them until they are sunk even if the South Koreans have to drop JDAMs on the vessels as they enter North Korean ports.
At some point, South Korea has to send the message that they won't just meekly accept attacks and deaths and hope the North Koreans go away.
