"It was eerie," said David M. Finkelstein, director of Project Asia at the Alexandria, Va., nonprofit research center CNA Corp. and a former Army officer posted at the Panmunjom truce village in the early 1980s. "I was absolutely amazed at how wide and high the tunnel I visited was."
There haven't been any major discoveries in recent years, leading some to conclude the North has focused its tunnel-building exclusively inward.
Others aren't so sure, however, and accuse the South of hiding such finds in keeping with its accommodating "sunshine policy" toward its mercurial northern neighbor.
The fear that Northern soldiers might one day pop out of a Seoul or Incheon sewer has spurred on a small group of avid South Korean tunnel hunters who comb the country, poking microphones, cameras and lasers into the ground in search of the North's mole holes.