North Korean Anti-Personnel Box Mine (Wooden Box Mine)

1. Overview

The North Korean AP Box Mine is a wooden-cased, pressure-activated, blast-type anti-personnel landmine derived from Soviet PMD-series designs. Consisting of a simple wooden box containing a TNT explosive charge and a mechanical fuze, it represents one of the most basic and enduring mine designs in use worldwide. Despite its crude construction, the box mine is a persistent and dangerous threat — it is extremely difficult to detect with metal detectors due to its minimal metal content, and it has been employed by North Korean forces in the Korean Demilitarized Zone (DMZ) from the Korean War era through to the present day.

⚠ SAFETY WARNING: All ordnance should be considered dangerous until proven safe by qualified personnel. Wooden box mines may appear degraded but can remain fully functional. Suspected mines should never be handled by untrained individuals and must be reported to military or law enforcement authorities immediately. This information is for educational and identification training purposes only.

2. Country/Bloc of Origin

  • Country: Democratic People’s Republic of Korea (North Korea)
  • Design Origin: Based on the Soviet PMD-6 and PMD-6M wooden box mine series, developed by the Soviet Union in the late 1930s
  • Era: The Soviet PMD-6 was first used in the 1939 Winter War against Finland; North Korea adopted the design during the Korean War (1950–1953) and continues to produce and deploy variants to the present day
  • North Korean Production: Manufactured domestically using simple materials (wooden box, TNT or mixed explosive, mechanical fuze); known locally by the term “Trotsil” (Тротил), a transliteration of the Russian word for TNT

3. Ordnance Class

  • Type: Anti-personnel landmine (blast)
  • Primary Role: Area denial against dismounted personnel; defensive barrier obstacle
  • Deployment Method: Hand-emplaced, buried at or just below ground surface

4. Ordnance Family / Nomenclature

  • Common Names: North Korean Wooden Box Mine, AP Box Mine, NK Box Mine
  • Soviet Ancestor Designations:
    • PMD-6 — Original Soviet version (1939); 200g TNT, ~460–490g total weight
    • PMD-6M — Slightly larger version with internal leaf spring for increased operating pressure (safer handling during emplacement)
    • PMD-7ts — Solid wooden block variant hollowed to accept charge and fuze
    • PMD-57 — Later, larger Soviet box mine variant (400g explosive, 620g total weight)
  • North Korean Variants: No official Western designation has been assigned to North Korean production variants. They are generally described as PMD-type wooden box mines with construction details varying by production batch
  • Related North Korean Mine: ATM-74 — A North Korean wooden box anti-tank mine (copy of Soviet TMD-B), significantly larger (9 kg, 6 kg TNT, operating pressure 200–500 kg)
  • Fuze Compatibility: MUV-series mechanical pull/pressure fuzes (MUV-1 through MUV-4); Soviet UV and UVG fuze series

5. Hazards

  • Primary Hazard Types:
    • Blast: The TNT charge (typically 70–200g in AP variants, up to 400g in PMD-57 type) produces a localized blast sufficient to cause traumatic amputation of the foot/lower leg and severe injury to the victim and nearby personnel
  • Detection Difficulty:
    • Extremely low metal content — the only metal components are the fuze’s small striker, retaining pin, and detonator cap
    • Virtually undetectable by 1940s-era metal detectors; modern high-sensitivity detectors (e.g., Ebinger 420) can detect them at short range (~30m ground-penetrating), but practical field detection remains very challenging
    • Wooden construction provides no metallic signature
  • Degradation and Unpredictability:
    • The wooden case is vulnerable to rotting, splitting, and water damage, which can render the mine inoperable over time in wet climates
    • However, in dry conditions, PMD-type mines have been found fully operational up to 10 years after emplacement
    • Degradation is unpredictable — a mine may appear rotted but retain a functional fuze and explosive charge
    • Water-damaged mines may be unstable if the explosive filler has degraded or the fuze mechanism is corroded
  • Flooding/Displacement Hazard:
    • Box mines are susceptible to being washed away by flooding and heavy rains from their original emplacement sites
    • North Korean box mines have been recovered on South Korean beaches, riverbanks, and civilian areas after being displaced by floodwaters from the DMZ
    • In 2010, two fishermen in the Imjin River basin picked up a displaced North Korean box mine, resulting in one death and one serious injury
    • In 2015, two South Korean staff sergeants were seriously injured by North Korean box mines found on the south side of the DMZ
  • UXO Considerations:
    • Extremely common throughout the Korean DMZ and border areas
    • An estimated 1 million landmines exist in the DMZ (all types combined)
    • The simple construction means replacement or improvised explosive charges (including mortar bomb explosive) can be substituted for standard TNT blocks
    • Separated fuze components and explosive blocks may be encountered independently

6. Key Identification Features

  • Shape: Rectangular wooden box with a hinged lid
  • Dimensions (PMD-6 type):
    • Length: 19–20 cm
    • Width: 9 cm
    • Height: 4–5 cm
    • Weight: 460–490g
  • Dimensions (PMD-57 type):
    • Length: 11.5 cm
    • Width: 11.3 cm
    • Height: 7.5 cm
    • Weight: 620g
  • Construction: Unfinished or roughly finished wooden box; quality varies with production batch; may show evidence of hand construction
  • Lid Mechanism: Hinged top lid with a slot cut into it; the slot presses down against a retaining pin
  • Explosive Block: Rectangular TNT block fitted inside the box, with a space at one end for the detonator and fuze. Explosive dimensions (PMD-6): approximately 10 cm × 5 cm × 2 cm
  • Color: Natural wood color; no paint or markings (contributes to camouflage)
  • Fuze: Small mechanical fuze (MUV-series or similar) visible inside the box when the lid is opened; includes a metal striker and retaining pin
  • Evidence of North Korean Origin (per 2015 investigation): Investigation of mines recovered from the DMZ identified specific design characteristics of wood cases, spring parts, and TNT as consistent with North Korean military production

7. Fuzing Mechanisms

  • Activation Type: Pressure-activated (lid depression)
  • Mechanism:
    1. The wooden lid is hinged on one side
    2. A slot in the underside of the lid aligns with a metal retaining pin inside the box
    3. The retaining pin holds back a spring-loaded striker
    4. When sufficient downward force (pressure) is applied to the lid (from a footstep), the lid depresses and the slot pushes against the retaining pin
    5. The retaining pin is displaced, releasing the striker
    6. The striker impacts the detonator, which initiates the TNT main charge
  • Operating Pressure:
    • PMD-6: 6–28 kg when stepped on; 1–12 kg when lid is opened (lower threshold)
    • PMD-57: 1–12 kg
    • The lower threshold for lid-opening versus stepping demonstrates the mine’s dual-purpose capability (mine and booby trap)
  • Fuze Types: MUV-1 through MUV-4 series mechanical fuzes; UV and UVG series
  • PMD-6M Enhancement: The PMD-6M variant includes a leaf spring inside the box that increases the operating pressure required, making it safer to handle during emplacement
  • Self-Destruct/Self-Neutralization: None. The mine relies on natural degradation of the wooden case for eventual neutralization, which is unreliable and may take years or decades depending on environmental conditions

8. History of Development and Use

The wooden box mine concept originated with the Soviet PMD-6, designed in the late 1930s. The design was intentionally simple enough to be mass-produced in ordinary factories without specialized tooling. The PMD-6 was first used against the Finnish Army in the Winter War (1939) and subsequently deployed in enormous quantities against the German Wehrmacht during the Great Patriotic War (1941–1945), where its near-undetectability by period metal detectors made it a devastatingly effective area denial weapon.

The explosive filler varied by factory — some used pure TNT, others used 80/20 blends of melinite and dinitronaphthalene, or 70/30 or 50/50 blends of TNT and trinitroxylene, though the weight never exceeded 200g in the PMD-6.

North Korea received PMD-series mines from the Soviet Union and adopted the design for domestic production. During the Korean War (1950–1953), box mines were used extensively by North Korean and Chinese forces. The mines were particularly effective because they could be manufactured quickly using local materials and were nearly invisible to the mine detection equipment of the era.

North Korean forces continued to emplace box mines in the DMZ throughout the Cold War and beyond. The DMZ remains one of the most heavily mined areas in the world. Notable incidents include:

  • August 4, 2015: Two South Korean staff sergeants were seriously injured by North Korean wooden box mines on the south side of the DMZ near Paju. Investigation confirmed the mines were North Korean military production based on the design of the wood cases, spring components, and TNT filler. The mines appeared to have been freshly emplaced by North Korean soldiers who crossed the Military Demarcation Line.
  • 2010: Two fishermen in the Imjin River basin recovered a North Korean box mine displaced by heavy rain, resulting in one death and one serious injury.
  • 2024: North Korean forces were observed emplacing tens of thousands of mines in the DMZ, including box mines and the newer “leaf mine” variant. Multiple North Korean casualties occurred during emplacement operations due to inadvertent detonations.

The wooden box mine design has been adopted beyond North Korea — it was copied by Rhodesia during the Bush War (to evade arms embargoes), and variants have been documented in Albania, Algeria, Ecuador, Eritrea, and Nicaragua.

9. Technical Specifications

ParameterPMD-6 TypePMD-57 Type
TypeAP blast mineAP blast mine
ConstructionWooden box, hinged lidWooden box, hinged lid
Length19–20 cm11.5 cm
Width9 cm11.3 cm
Height4–5 cm7.5 cm
Total Weight460–490g620g
Explosive Fill200g TNT (or mixed)400g TNT (or mixed)
Operating Pressure6–28 kg (stepped); 1–12 kg (opened)1–12 kg
FuzeMUV-1 through MUV-4UV, UVG, MUV series
Metal ContentMinimal (striker, pin, detonator)Minimal
Body MaterialUnfinished woodUnfinished wood

10. Frequently Asked Questions

Q: Why does North Korea continue to use such a primitive mine design? A: The wooden box mine’s simplicity is its greatest tactical advantage. It can be manufactured with minimal industrial capability, uses commonly available materials (wood and TNT), requires no specialized components, and is extremely difficult to detect with metal detectors. For a resource-constrained military like North Korea’s, the box mine provides maximum area denial effect for minimum cost and industrial investment. Its effectiveness has been proven over more than 80 years of use.

Q: How does the box mine’s near-zero metal content affect clearance operations? A: The minimal metal content (only the fuze striker, retaining pin, and detonator cap) makes the box mine extremely challenging to detect with standard metal detectors. Modern high-sensitivity detectors can detect the small metal components, but only at short range and in ideal soil conditions. Ground-penetrating radar and trained mine detection dogs are more reliable detection methods for wooden-cased mines. Manual probing is another technique, though it is slow and hazardous.

Q: Why are box mines particularly dangerous after flooding? A: Heavy rains and flooding can dislodge buried box mines from their emplacement sites and carry them downstream into uncontrolled areas — including South Korean civilian territory. The mine may still be fully functional after displacement, but its location is now unknown and uncharted. Anyone who encounters a water-displaced mine has no warning they are in a mined area. The 2010 Imjin River incident and the 2024 concerns about DMZ mines washing into South Korea during monsoon rains highlight this hazard.

Q: Can you tell how old a wooden box mine is by its condition? A: Not reliably. While wooden cases do degrade over time, the rate depends entirely on local soil moisture, temperature, and exposure. A mine in dry, sandy soil may look nearly new after years. A mine in wet conditions may appear heavily degraded but still contain a functional fuze and explosive charge. The external condition of the wooden case is NOT a reliable indicator of the mine’s operational status. All box mines should be treated as functional regardless of apparent age or condition.

Q: What is the difference between the AP box mine and the ATM-74 anti-tank box mine? A: The ATM-74 is a much larger North Korean wooden box mine designed to defeat vehicles. It weighs 9 kg with 6 kg of TNT and requires 200–500 kg of pressure to activate (vehicle weight). The AP box mine weighs less than 1 kg with 70–400g of explosive and activates at 1–28 kg (foot pressure). While both use wooden construction and similar fuzing concepts, they are designed for completely different targets and produce very different effects.

Q: How was the 2015 DMZ box mine incident attributed to North Korea? A: South Korean military investigators identified the mines as North Korean based on the specific design and construction details of the wooden cases, the configuration of three spring parts, and the type of TNT explosive material found at the explosion site. The investigation, led by Army Brigadier General Ahn Young-ho, concluded the mines were consistent with wooden box mines in the North Korean military inventory and had been deliberately placed across the MDL.

Q: What is “Trotsil” and why is it associated with North Korean box mines? A: “Trotsil” (트로찔) is a Korean transliteration of the Russian word “Тротил” (Trotil), which is an abbreviation for Trinitrotoluol — in other words, TNT. In North Korean military terminology, the box mine is commonly referred to by this explosive filler name. The term reflects the direct Soviet lineage of the mine and North Korea’s adoption of Russian military nomenclature.

Q: Were wooden box mines used by any forces other than Soviet/Communist bloc militaries? A: Yes. The design’s simplicity made it attractive to other forces. Germany developed its own wooden box mine, the Schu-mine 42, containing 200g of explosive during WWII. Rhodesia produced copies of the PMD-6 during the Bush War to evade arms embargoes. The concept of a wooden-cased mine with minimal metal has been replicated independently by various forces worldwide due to its effectiveness against detection.