On November 15, 1974 a squad of South Korean soldiers stationed near Korangpo-ri, on the Korean demilitarized zone, noticed steam rising from the earth’s surface near to where they were camped out.
Lt. Col. Michael Wikan, who served as a G-3 operations officer in Korea, recounted what happened next in the book Espionage and the United States During the 20th Century , by Thomas Murray:
one of the ROK soldiers with sharp eyes noticed the heat waves rising from the ground and went to the location to investigate. When he heard voices up from the small hole, he fastened his bayonet to his rifle and probed—and more earth crumbled. When he fired his rifle into the hole, a volley of North Korean bullets flew back at him from the tunnel—and then silence. The South Korean squad reported the incident and dug a hole to open the tunnel, but no one entered.
South Korean troops across the 160-mile-long DMZ had overheard explosions and subterranean activity for over a year, and noticed heavy digging equipment moving around on the North Korean side of the border. This, however, was the first tunnel to be located—but nobody was in a rush to find out what was inside.
Five days later, the United Nations Command dispatched U.S. Navy Cdr. Robert M. Ballinger and Marine Maj. Anthony Nastri to inspect the tunnel. Because protocol required that they remain unarmed, they were escorted by troops led by Korean Marine Maj. Kim Hah-chul. All three officers were veterans of the Vietnam War. Wikan continues:
Bob lowered himself into the hole first, followed by Tony. Less than a minute later [at 1:20 PM], a huge explosion went off that killed Bob instantly. The South Korean soldiers quickly pulled Tony out of the hole.
We could never determine the exact type of explosive device that was involved, whether a booby trap, mere blasting materials, or a command-detonated mine. I have always believed they dug some blasting explosives into a sidewall and electrically detonated it from a distance.
Major Kim was also killed in the blast, and five U.S. troops and one Korean were wounded.
Later inspections revealed the so-called First Tunnel of Aggression had been lavished with concrete-slab walls, electrical lighting, weapon-storage areas and sleeping accommodations. There was even a railway with carts installed. The tunnel was over two miles long, a third of which was on the South Korean side of the border, and had space enough for two thousand soldiers to traverse it per hour.
According to a South Korean defense white paper , Kim Il-sung had ordered the tunnel building campaign in a meeting on September 25, 1971, proclaiming somewhat optimistically, “One tunnel can be more powerful and effective than ten atomic bombs put together and the tunnels are the most ideal means of penetrating the South’s fortified front line.” The tunnel-building campaign was supposed to be completed by 1975.
The underground passageways could be used in peace to funnel agents into South Korea or in war to enable commando and light infantry units to bypass the heavy fortifications of the DMZ, cutting South Korean logistical lines and creating a “second front line” that reinforcements would have to fight through.
Four months after the first tunnel was discovered, a much larger tunnel was discovered thirteen miles north of Cheorwon, at the center of the demilitarized zone. Subterranean explosions had been heard there for over three years. Finally, South Korean troops combing the area dug an intercept tunnel in March 1975. This second tunnel penetrated one mile over the DMZ and measured nearly two by two meters in size, with a vaulted ceiling—ostensibly large enough to accommodate small vehicles and artillery, or to disgorge thirty thousand troops per hour under the border into South Korea. A large troop-assembly area was carved out, and there were three separate exits to facilitate a rapid flow of troops.
The Third Tunnel of Aggression, the most famous, was discovered in 1978 , just twenty-seven miles north of Seoul, within a couples miles of the “truce village” of Panmunjom and the American Camp Kitty Hawk. South Korean troops had been searching the areas for several years based on the account of a defector named Kim Pu-song. The tunnel was finally located on June 10, when North Korean tunneling activity caused a jet of water to burst open the covering of an older South Korean bore hole. This Third Tunnel, which was 240 feet deep and penetrated four hundred meters past the DMZ, was of similar design to the second tunnel, and was well positioned for launching a surprise attack on the South Korean capital.