South Korean civilians are afraid of their government's non-response to the civilians' discovered the N.K's underground tunnels(ddanggul) at the urban area(s) of their capital city Seoul.
According to sources, a number of underground tunnels are ready for sneaky attacking to US military base wherein US citizens have their residency, Yongsan Garrison.
http://www.ddanggul.com says all the undergraound tunnel stories.
What is your countermeasures in case of the North Korea's ddanggul operation performed?