Smuggling Tunnels DMZ 2023- A Comprehensive Guide

DMZ Smuggling Tunnels: How to locate the smuggling tunnels on Al Mazrah

Smuggling Tunnels: The Korean Demilitarized Zone (DMZ) is a heavily fortified strip of land running across the Korean Peninsula, separating North Korea and South Korea. It was established at the end of the Korean War in 1953 as a buffer zone between the two Koreas. The DMZ is about 4 km wide and 248 km long and is considered one of the most militarized borders in the world.

Despite its high security, over the years there have been several incidents of North Koreans tunneling under the DMZ to infiltrate South Korea. These secret tunnels have been used for smuggling operations, spy missions, and even for potential military invasions. Detecting and locating these smuggling tunnels in the DMZ has been an ongoing effort by South Korea and the United Nations Command (UNC).

History of DMZ Tunnels/Smuggling Tunnels

The first DMZ smuggling tunnel was discovered in 1974. This tunnel, now known as the First Tunnel of Aggression, ran from North Korea under the DMZ into South Korea. It was large enough for thousands of soldiers per hour to pass through and was dug as an invasion route. After its discovery, 3 more invasion tunnels were found before 1990.

Since the 1990s, several smaller tunnels believed to be used for smuggling operations have also been detected. These include tunnels found in 1998, 2003, 2006, and 2020. Goods like drugs, weapons, counterfeit money, and cigarettes were smuggled through them from North to South Korea. The frequency of tunnel discoveries shows the determination of North Korea to circumvent the DMZ.

Methods Used to Locate Tunnels

Several techniques have been employed over the years to find these illicit cross-border tunnels:

Ground Surveys – Patrols monitor the DMZ area on the ground, looking for signs of digging activity or collapsed ground that may indicate a tunnel. Guard posts are set up at regular intervals too.

Seismic Sensors – Networks of underground seismic sensors monitor for vibrations and seismic anomalies consistent with digging activity. Seismic trucks also investigate potential tunnel construction sites.

Electromagnetic Surveys – Metal detection surveys and ground-penetrating radar searches are conducted to profile underground structures. Abnormalities are flagged for further investigation.

Excavations – Promising sites are excavated to search for tunnel entry points. This has led to the discovery of several smuggling tunnels.

Tip-offs – South Korea also receives intelligence tip-offs from informants and defectors about potential tunnel locations. This inside information helps target search areas.

Notable DMZ Tunnels

Here are some details on a few of the most well-known tunnels found under the DMZ over the years:

First Tunnel of Aggression

  • Located: 1978 after tip-off
  • Location: 52km southeast of Pyongyang
  • Length: about 1.7 km long, 2 m high x 2 m wide
  • Depth: 73 m below ground
  • Capacity: Allow 30,000 troops per hour

Second Tunnel of Aggression

  • Located: 1990 through seismic sensors
  • Location: 59 km northeast of Seoul
  • Length: About 1.1 km long
  • Depth: 152 m below ground

Third Tunnel of Aggression

  • Located: 1978 through electromagnetic survey
  • Location: 44 km northeast of Seoul
  • Length: 1.6 km long
  • Depth: 83 m below ground

Ganggyeong Sokhang Tunnel

  • Located: 2020 through excavation
  • Location: 26 km north of Dongducheon
  • Size: believed to be big enough for personnel passage
  • Depth: 22 m below ground

Goseong Unification Tunnel

  • Located: 1990 after tip-off
  • Location: 66 km northeast of Pyongyang
  • Size: small, around 1 m in diameter
  • Depth: 88 m below ground
  • Used for smuggling activities

Dorasan Tunnel

  • Located: 2006 during a routine patrol
  • Location: 700 m southeast of Dorasan Station
  • Size: 1.6 m x 1.2 m
  • Depth: 73 m below ground
  • Likely used for smuggling due to the small size

Ongoing Efforts to Detect Tunnels

Locating these clandestine tunnels remains a priority for security forces patrolling the DMZ. South Korea continues to invest heavily in tunnel detection capabilities and technology.

In 2020, South Korea decided to double its investment in anti-tunnel detection and surveillance equipment after the recent discovery of the Ganggyeong tunnel. Advanced sonar, seismic sensors, and drilling equipment will augment the currently deployed sensors.

The UNC has also increased ground patrols looking for signs of underground activity. However, most tunnels are dug deep underground, making them difficult to detect even with new equipment.

North Korea also continues aggressive tunneling operations. Several suspected tunnels have been detected through intelligence reports but remain unverified. Locating these rumored tunnels will require systematic surveys across vulnerable sectors of the DMZ.

Going forward, tunnel detection will remain a key part of safeguarding the DMZ. Any illegal tunnels allowing infiltration must be quickly located and sealed to uphold the DMZ’s integrity as a fortified border zone.

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FAQ on Tunnels in the DMZ

Here are some frequently asked questions about locating smuggling tunnels under the Korean Demilitarized Zone:

How many tunnels are there under the DMZ?

  • At least 4 major invasion tunnels have been found so far, along with several smaller smuggling tunnels. The actual number is unknown. Estimates range from around 10 to over 20 undiscovered tunnels.

What technology is used to find the tunnels?

  • Ground penetrating radar, seismic sensors, electromagnetic surveys, and excavations are used. Advanced sonar and drilling equipment have also been deployed recently.

How deep are the tunnels?

  • Discovered tunnels are 50 to 150 meters underground, deep enough to avoid detection. The deepest is the 2nd tunnel at 152 m below ground.

How are the tunnels constructed?

  • Most are dug through solid granite bedrock. They are reinforced with concrete walls, electrical lighting, and ventilation ducts. Rail systems move excavated rock and soil.

Could the tunnels be used for invasion?

  • The 4 larger tunnels found could allow thousands of troops per hour to cross the DMZ undetected. However, most are now sealed or guarded. Smaller smuggling tunnels remain a security risk.

Are new tunnels still being dug?

  • It’s likely North Korea still actively digs tunnels. Construction was detected as recently as 2020. Several rumored tunnels also remain unlocated across the DMZ.

How are tunnels sealed once found?

  • Tunnels are blocked with concrete walls, barricades, or explosives to prevent access. Some are converted to tourist sites. Motion sensors monitor sealed tunnels.

Are ground surveys the most effective detection method?

  • Yes, ground patrols can identify digging activity most directly. However seismic sensors and radar are useful for wide-area surveillance. Excavation confirms tunnel locations.


For over 50 years, North Korea has attempted to infiltrate the DMZ through elaborate smuggling and invasion tunnels beneath the heavily fortified border zone. Locating these illicit tunnels remains vital to security. While over 20 tunnels have been found so far, North Korea likely has dozens more tunnels that have avoided detection.

Going forward, the search for clandestine DMZ tunnels will continue using a combination of ground surveys, seismic sensors, electromagnetic surveys, and excavations. Advanced tunnel detection technology like ground-penetrating radar and sonar are also being deployed. However, the task remains challenging due to the depth and sophistication of the tunnels.

Maintaining constant vigilance will be key to intercepting any future tunnels dug across the DMZ. As long as the Korean border remains divided, the DMZ will have to stay closely monitored as both a diplomatic meeting point and a military flashpoint between the North and South. Smuggling and infiltration tunnels, if left undetected, could destabilize security on the peninsula. Continued tunnel detection efforts uphold the integrity of the DMZ as a secure barrier vital to regional peace.

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