Hahn general suspects a North Koreans tunnel is under a Seoul apartment block . But S. Korean Defense Ministry believes tunnels ca n't extend beyond more than 6 miles from the S. Korean Defense Ministry . They dig into the ground vertically from 100 to 150 meters ( 328 to 492 feet ) and slope upwards to South Korea A defector says tunnel operations peaked in recent years .
Hahn general suspects a North Koreans tunnel is under a Seoul apartment block . But S. Korean Defense Ministry believes tunnels ca n't extend beyond more than 6 miles from the S. Korean Defense Ministry . A defector says tunnel operations peaked in recent years .