BLU-43 Submunition (Dragontooth)

1. Overview

The BLU-43/B “Dragontooth” is a United States air-delivered anti-personnel mine/submunition designed for area denial through covert emplacement. Unlike conventional fragmentation submunitions that detonate on impact, the BLU-43 is designed to land intact and function when disturbed by personnel, effectively operating as an air-scattered landmine. Its distinctive delta-wing shape, designed for stabilized descent, creates an item that can be mistaken for a toy or leaf, tragically increasing risk to civilians, particularly children. The BLU-43 represents the intersection of cluster munition and landmine technologies.

2. Country/Bloc of Origin

  • Country of Origin: United States of America
  • Development Period: 1960s
  • Manufacturer: Produced under U.S. Department of Defense contracts
  • Development Driver: Vietnam War requirement for area-denial weapons deliverable by aircraft
  • Proliferation: Primarily U.S. forces; limited export to allied nations
  • Related Foreign Development: Soviet PFM-1 “butterfly mine” served similar function with similar shape

3. Ordnance Class

  • Type: Air-delivered anti-personnel mine / Submunition
  • Role: Area denial through anti-personnel mine effect
  • Category: Scatterable mine; cluster munition payload element
  • Dual Classification: Functions both as submunition (delivery method) and landmine (operational mode)
  • Delivery Methods:
    • CBU-28 cluster bomb unit
    • CBU-37 cluster bomb unit
    • SUU-41 dispenser
    • Dispensed from tactical aircraft

4. Ordnance Family / Nomenclature

Primary Designation

  • BLU-43/B – Standard production “Dragontooth”
  • Nomenclature Breakdown:
    • BLU: Bomb Live Unit
    • 43: Model number
    • /B: Standard variant suffix

Related Variants

  • BLU-44/B – Identical to BLU-43 but filled with improved explosive
  • XM-41 – Army developmental designation (same device)
  • XM-44 – Developmental designation for variant

Related Systems (Similar Role)

  • BLU-54/B – Larger air-delivered scatterable mine
  • GATOR System (BLU-91/BLU-92) – Later generation air-delivered mines
  • Soviet PFM-1 “Butterfly Mine” – Functionally similar Soviet system

Parent Munitions

  • CBU-28/A – Cluster bomb unit for BLU-43 delivery
  • CBU-37/A – Alternate dispenser configuration

Common Names

  • “Dragontooth” – Official nickname
  • “Spider” – Less common reference
  • “Button mine” – Reference to pressure-activated function

5. Hazards

Primary Hazards

  • Blast Effect: Small explosive charge sufficient to destroy foot or lower leg
  • Fragmentation: Minimal; casing does not produce significant fragmentation
  • Maiming Injuries: Designed to incapacitate through traumatic amputation rather than kill outright

Sensitivity Concerns

  • Pressure Sensitivity: Activates with approximately 5-12 kg (11-26 lbs) of pressure
  • Low Activation Threshold: Weight of child can activate the device
  • Cumulative Pressure Effect: Liquid explosive may become more sensitive over time
  • Environmental Exposure: Weathering can affect fuze reliability unpredictably
  • Handling Danger: Any manipulation of armed device risks detonation

Danger Areas

  • Injury Radius: Localized; severe injury to person in contact
  • Blast Effect Range: Approximately 1-2 meters for secondary injury from blast pressure
  • Fragmentation Range: Minimal; not significant fragmentation hazard beyond immediate contact

UXO Considerations

  • Design Intent: Unlike impact-fuzed submunitions, BLU-43 is INTENDED to remain unfired until disturbed
  • Long-Term Hazard: Functions as persistent landmine; dangerous for decades
  • Camouflage: Delta-wing shape and colors can blend with leaves and debris
  • Child Attraction: Shape and size may be mistaken for toy, causing tragic accidents
  • Dud Rate: Separate from “traditional” dud rate—even devices that land intact but fail to function on disturbance remain dangerous

6. Key Identification Features

Physical Characteristics

  • Shape: Distinctive delta-wing (triangular) planform
  • Length: Approximately 89 mm (3.5 inches) along central axis
  • Wingspan: Approximately 76 mm (3 inches) across widest point
  • Thickness: Approximately 19 mm (0.75 inches)
  • Weight: Approximately 19-20 grams (0.7 oz)

External Features

  • Body Material: Injection-molded plastic (polyethylene or similar)
  • Wing Configuration: Two extended wings for aerodynamic stabilization during descent
  • Central Body: Thicker center section housing explosive fill
  • Fuze Area: Pressure-sensitive area on upper or lower surface
  • Detonator Housing: Integrated into plastic body

Color and Markings

  • Body Colors:
    • Olive drab (most common)
    • Brown
    • Sand/tan
    • Gray-green
    • Colors selected to blend with terrain in target area
  • Markings: Minimal; small lot/date stamps if any
  • Camouflage Intent: Coloring deliberately chosen to reduce visibility

Distinctive Identification Points

  • Unique delta-wing “butterfly” or “bat” shape
  • Very small and lightweight (smaller than palm of hand)
  • Plastic construction (lightweight feel)
  • May show signs of weathering if exposed for extended period
  • Central thickened body with thin extended wings

Appearance Hazard

CRITICAL: The BLU-43’s shape resembles a toy or leaf, making it particularly dangerous to children who may pick it up. This appearance hazard has caused numerous child casualties.

7. Fuzing Mechanisms

Primary Fuze Type

  • Activation Type: Pressure-actuated
  • Mechanism: Pressure on mine body compresses internal bladder/chamber, actuating detonator
  • Threshold: Approximately 5-12 kg (11-26 lbs) pressure required

Explosive System

  • Fill Type: Liquid explosive (typically tetryl or similar in solution)
  • Fill Weight: Approximately 5.5 grams
  • Detonator: Integrated stab-sensitive detonator activated by pressure

Arming Sequence

  1. BLU-43 retained in dispenser during aircraft carriage
  2. Dispenser opens at designated altitude
  3. Submunitions ejected; wings stabilize descent, slowing fall
  4. Device lands and remains in armed state
  5. Device detonates when stepped on or disturbed with sufficient pressure

Safety Features

  • In-Dispenser Safety: Mechanical retention prevents function while stored
  • Arming Delay: Brief delay allows separation from aircraft
  • Stabilized Descent: Wings ensure device lands in proper orientation

Self-Neutralization

  • Design Claim: Some sources indicate self-neutralization feature intended after certain period
  • Reliability: Self-neutralization extremely unreliable in practice
  • Practical Reality: Devices have remained functional for decades
  • DO NOT RELY on self-neutralization: All BLU-43s must be treated as armed and dangerous regardless of age

8. History of Development and Use

Development Background

The BLU-43 emerged from Vietnam War requirements for air-delivered area denial weapons. Traditional landmines required ground forces for emplacement, limiting their tactical flexibility. The concept of scatterable mines deliverable by aircraft offered the ability to rapidly deny areas to enemy movement without exposing friendly forces.

Design Philosophy

  • Deny terrain to enemy personnel
  • Create “no-go” zones along infiltration routes
  • Harass and demoralize enemy forces
  • Slow movement through contaminated areas
  • Force time-consuming clearance operations

Vietnam War Employment

The BLU-43 was employed primarily:

  • Along the Ho Chi Minh Trail supply routes in Laos
  • Border areas of Vietnam and Cambodia
  • Infiltration routes used by North Vietnamese forces
  • Interdiction zones to disrupt logistics

Operational Controversies

The BLU-43 attracted controversy due to:

  • Function as de facto landmine rather than conventional bomb
  • Inability to discriminate between combatants and civilians
  • Long-term persistence creating post-conflict hazard
  • Appearance attractive to children
  • Difficulty in clearance and marking

Comparison to Soviet PFM-1

The Soviet Union developed the remarkably similar PFM-1 “butterfly mine” serving the same role. The PFM-1 was extensively used in Afghanistan (1979-1989), causing widespread civilian casualties, particularly among children attracted by its shape. The parallel development and similar humanitarian consequences of both systems illustrate the inherent problems with scatterable anti-personnel mines.

International Response

  • BLU-43 and similar air-scattered mines contributed to international concern leading to the Ottawa Treaty (1997) banning anti-personnel landmines
  • United States has not signed the Ottawa Treaty
  • Convention on Cluster Munitions (2008) also addresses such weapons
  • Both systems cited in humanitarian advocacy against scatterable mines

Current Status

  • U.S. Inventory: Largely withdrawn from active inventory
  • UXO Contamination: Remains present in Laos and other Southeast Asian areas
  • Clearance Challenges: Small size and camouflage coloring make detection difficult
  • Continuing Casualties: Incidents still occur in contaminated regions

9. Technical Specifications

SpecificationValue
DesignationBLU-43/B “Dragontooth”
TypeAir-scattered anti-personnel mine/submunition
ShapeDelta-wing (triangular)
Length~89 mm (3.5 in)
Wingspan~76 mm (3 in)
Thickness~19 mm (0.75 in)
Weight~19-20 g (0.7 oz)
Body MaterialInjection-molded plastic
Explosive FillLiquid explosive (tetryl-based)
Explosive Weight~5.5 g
Fuze TypePressure-actuated
Activation Pressure~5-12 kg (11-26 lbs)
Intended EffectTraumatic amputation/maiming
Self-NeutralizationClaimed but unreliable
DispenserCBU-28, CBU-37

10. Frequently Asked Questions

Q: Why is the BLU-43 called a “Dragontooth”? A: “Dragontooth” is the official U.S. military nickname for the BLU-43. The name evokes the Greek myth of Cadmus, who sowed dragon’s teeth that grew into armed warriors. Similarly, the BLU-43 is “sown” from the air and creates a field of armed devices waiting to harm anyone who disturbs them. The name captures both the scattering method and the hostile purpose of the weapon.

Q: How does the BLU-43 differ from conventional fragmentation submunitions? A: Unlike fragmentation submunitions (such as the BLU-26) that detonate on impact with the ground, the BLU-43 is designed to land intact and remain armed, functioning only when disturbed by a person. This makes it functionally a landmine rather than a bomb, operating through area denial rather than immediate attack. The target is personnel who enter the contaminated area after delivery, not targets present during the attack.

Q: Why is the BLU-43 particularly dangerous to children? A: The BLU-43’s delta-wing shape, small size, and camouflage coloring create deadly appearance hazards. To a child, the device may resemble a toy, a butterfly, or an interesting leaf or object worth examining. The low activation pressure (as little as 5 kg) means a child’s weight is sufficient to detonate it. Tragically, this has resulted in numerous child casualties in contaminated areas, particularly in Laos. Similar problems occurred with the Soviet PFM-1 in Afghanistan.

Q: What is the relationship between the BLU-43 and the Soviet PFM-1? A: The BLU-43 and Soviet PFM-1 represent parallel developments of the same concept—air-scattered, pressure-activated anti-personnel mines with similar wing-shaped configurations for stable descent. Both weapons emerged during the 1960s from similar tactical requirements. Both have created serious humanitarian problems due to high dud/persistence rates and child casualties. The PFM-1’s extensive use in Afghanistan created comparable contamination to BLU-43 use in Laos.

Q: Does the BLU-43 have a self-destruct or self-neutralization feature? A: Some documentation indicates the BLU-43 was designed with a self-neutralization feature intended to render it safe after a certain period. However, this feature has proven extremely unreliable in practice. BLU-43 devices have remained functional for decades after emplacement. For EOD and clearance purposes, all BLU-43s must be treated as armed and dangerous regardless of age. Self-neutralization claims should never be relied upon.

Q: How is the BLU-43 detected and cleared? A: The BLU-43 presents significant clearance challenges. Its small size, plastic construction, and minimal metal content make detection with conventional metal detectors difficult. Ground-penetrating radar and other advanced detection methods have limited effectiveness. Visual search remains important, but camouflage coloring complicates this. Clearance requires systematic area searches by trained personnel. Once located, devices are typically destroyed in place through controlled detonation rather than moved, given their sensitivity.

Q: Is the BLU-43 considered a landmine under international law? A: Yes, functionally the BLU-43 operates as an anti-personnel landmine—it is victim-activated, remains in place waiting to harm anyone who disturbs it, and is designed to maim rather than kill outright. Under the 1997 Ottawa Treaty (Mine Ban Treaty), such weapons would be prohibited. However, the United States has not signed the Ottawa Treaty. The BLU-43 also falls under the Convention on Cluster Munitions (2008), which the U.S. has also not signed. The device’s dual nature—delivered as a submunition but functioning as a mine—highlights limitations in categorical definitions.

Q: What injuries does the BLU-43 typically cause? A: The BLU-43 is designed as a maiming weapon rather than one intended to kill outright. The small explosive charge is positioned to destroy the foot and lower leg of someone stepping on the device. This causes traumatic amputation, severe soft tissue injury, and often results in permanent disability. While potentially survivable with prompt medical care, the injuries are devastating and life-altering. In areas with limited medical access, such injuries can still prove fatal due to blood loss and infection.

Q: Where are BLU-43s still found today? A: The primary contamination exists in Laos along former Ho Chi Minh Trail routes, where extensive air-scattered mine operations occurred during the Vietnam War. Devices may also exist in border regions of Vietnam and Cambodia, and potentially in areas where U.S. stocks were held or tested. Due to the small size and persistence of these devices, contamination remains a serious concern decades after the conflict ended. Humanitarian clearance operations continue, but complete remediation remains a long-term goal.

This lesson is intended for educational purposes in professional ordnance training contexts. All ordnance should be considered dangerous until assessed and rendered safe by qualified EOD personnel. Never approach, handle, or disturb suspected unexploded ordnance. The BLU-43’s resemblance to a toy makes it particularly dangerous—community education about this threat is critical in contaminated areas.