South Korea is alarmed at the increase in North Korea infiltration attempts (by agents, Internet hackers or UAVs) into South Korea. Since 1953 (the end of the Korean War) South Korea has recorded over a thousand infiltration attempts by sea (often using small subs built just for that task) and over 700 by air (using aircraft and pilots selected and trained for delivering agents). There have also been a growing number of infiltration attempts across the theoretically impassable (because of all the mines, sensors, barbed wire and guards) DMZ (the five kilometer wide DeMilitarized Zone that stretches across the peninsula and marks the border between north and south Korea). The permeability of the DMZ was long known to intelligence officials but now it is becoming public knowledge and that is causing problems. This is especially true with latest form of intrusion; via the Internet.
Currently the South Korean military and intelligence agencies are making a big deal about all this infiltration and pointing out that better sensors and the North Korean use of the Internet for spying makes it easier to detect and count intrusion attempts. South Korea is detecting and catching (and sometimes turning into double-agents) more of these North Korean spies inside South Korea. More North Korea intelligence officials are getting out of North Korea and defecting to the south with details of past intrusions. In return for sanctuary they have to provide inside information that is verifiable and this stuff is not only true but scary. The defecting agents revealed a lot of North Korea intel efforts the south was never even aware of.
The North Korea intel efforts that fail in a public fashion are the ones that make the news, especially if someone gets killed. But it’s the ones you don’t know about that hurt you the most, especially the ones that succeed. So South Korea is trying to let more of its people know more about what to look for, especially since they are now learning about so many past intrusions they never realized occurred.