Explosive Ordnance

Unique identifier / Notation

SO0201

Synonyms

Unexploded ordnance Abandoned explosive ordnance Explosive Remnants of War ERW (sp) restos explosivos de guerra; munitcones sin detonar (Fr) Restes explosifs de guerre

Explosive ordnance, including explosive remnants of war, is interpreted as encompassing the following munitions: mines, cluster munitions, unexploded ordnance, abandoned ordnance, booby traps and other devices (IMAS 4.10) that remain in the environment following the cessation of armed conflict.

Explosive remnants of war refer to unexploded ordnance and abandoned explosive ordnance that are left by a party to an armed conflict following the cessation of warfare. Unexploded ordnance are munitions that have been primed, fused, armed or otherwise prepared for use, and may have been fired, dropped, launched or projected yet remain unexploded through malfunction or design or for any other reason. Abandoned ordnance refers to explosive ordnance that has not been used during an armed conflict but has been left behind or dumped. Mines are munitions designed to be placed under, on or near the ground or other surface area and to be exploded by the presence, proximity or contact of a person or a vehicle.

Primary reference(s)

United Nations Mine Action Service, 2024. International Mine Action Standards 01.10 (IMAS 04.10) Glossary of mine action terms, definitions and abbreviations International. Accessed 14 February 2025.

Annotations

Additional scientific description

The United Nations (2004) definition provided above is from Protocol V of the Convention on Certain Conventional Weapons but does not include any reference to explosive remnants of war (ERW) in the form of improvised explosive devices. However, these are mentioned as 'other devices' in amended Protocol II to the Convention on Certain Conventional Weapons.

'Explosive ordnance is a catchall term for any explosive ordnance that remains unexploded and abandoned following the cessation of conflict. An explosive ordnance may be considered 'unexploded' or 'abandoned' if it has been "primed, fused, armed, or otherwise prepared for use […] in an armed conflict" prior to being "left behind or dumped by a party to an armed conflict" (United Nations, 2004:2).

As of October 2024, at least 58 states and other areas (i.e., Abkhazia, Nagorno-Karabakh, Somaliland) were known or suspected to be anti-personnel landmine contaminated, while 26 states and 2 other areas had cluster munitions contamination, as of 31 December 2023 (Landmine & Cluster Munition Monitor, 2024a, b). A recent study examining explosive ordnance in over 100,000 casualties across 17 countries and other areas found a case fatality rate of 38.8 per 100 persons injured (Pizzino, 2024).

Cluster munitions are an example of ERW and have a long history of conventional use by state actors during warfare (UNODA, 2020a). They are "designed to cover an area with explosive force" and have been used in warfare since the Second World War (Bolton & Nash, 2010:175). A cluster munition produces damage by exploding a single projectile, which fragments into a number of smaller explosive ordnance, which then detonate over a large area (Bolton & Nash, 2010:175). Cluster munitions are of particular concern when discussing the impact of ERW, as the impact of unexploded cluster munitions when detonated is significantly higher than other conventional munitions. A study of the comparative impact on civilian populations found that "ten unitary projectiles with a 10 per cent failure rate will leave one unexploded item whereas ten cluster munitions with 100 submunitions each and a 10 per cent failure rate will leave 100 unexploded items - ten times as many" casualties or fatalities (Bolton & Nash, 2010:175). The clearance of cluster munitions has proved extremely challenging in many contexts - for example in Kosovo (ICRC, 2001:18) and Lao PDR, (UNDP Lao PDR, 2009) where civilians who went in search of provisions such as firewood accidentally detonated the munitions, causing many casualties and fatalities.

Explosive remnants of war also have adverse effects on populations owing to the shedding of chemicals or chemically active compounds into areas where they are abandoned. This can have long-term effects when a population is exposed to the chemicals through contamination of water, soil, food sources, and general living environment. One such example is the presence of depleted uranium, which has had significant impacts on the health of conflict-affected populations and their environment since it was introduced into conventional warfare (UNODA, 2020b). Depleted uranium has a high density, which makes it a useful component of kinetic energy weapons such as anti-tank weaponry (Murray et al., 2002). In areas with high radioactive contamination, there is a risk of wildfires burning terrain leading to an uncontrolled re-distribution of radioactive particles - which has a profound negative impact on population health. This has resulted in depleted uranium weapons being used widely with the exploded particle remnants being inhaled by those working and living in the vicinity of the conflict (Murray et al., 2002). The long-term effects of exposure to the remnants of depleted uranium from a health perspective are still unclear, but the environmental impact is profound - with an increase in uranium in water supplies, contaminated soil, and potentially unexploded remnants of depleted uranium munitions (Murray et al., 2002).

Metrics and numeric limits

UNMAS, the United Nations Mine Action Service, compiles data on casualties resulting from explosive ordnance (UNMAS, no date). For example the UNMAS Annual Report 2023 shares data on explosive ordnance casualties, contamination and most affected areas from UNMAS programmes in 20 countries (UNMAS, 2023).

Key relevant UN convention / multilateral treaty

The Convention on Cluster Munitions (2008) (Daj Hammarskjold Library, 2020);

the Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction (1997) (Daj Hammarskjold Library, 2020)

Convention on Certain Conventional Weapons (CCW) (1980) (Daj Hammarskjold Library, 2020).

Drivers

Explosive ordnances may be disseminated during floods and landslides (Baselt et al., 2023). Flooding can cause erosion of soil, potentially uncovering and carrying away previously buried ERWs, increasing the risk of contaminating new areas, or re-contaminating areas previously cleared (Njeri & Greene, 2024). Stockpiles of munitions may also explode during extreme heat events (Small Arms Survey, 2025)

Impacts

Explosive remnants of war have a profound impact on civilian populations and their environment well after the end of a conflict. Civilians in areas with ERW embedded in their environment are at risk of becoming casualties of explosive ordnance, potentially losing limbs or their lives (UNODA, 2020c). The presence of ERW restricts the movement of populations and hinders reconstruction, resulting in potentially limited access to arable land, food, water, care or trade (UNODA, 2020c).

Explosive remnants of war have an impact on the quality of water sources and arable land, as particulate matter from these remnants may infiltrate the environment – as in the case of depleted uranium weaponry (Murray et al., 2002). Explosive remnants of war pose a threat to people’s health and human rights in more than 60 lower- and middle-income countries (Frost et al., 2017). From 1999 through 2023, 159,445 mine and ERW casualties have been recorded, and 24,502 cluster munitions casualties have been recorded to the end of 2023. Annual casualty numbers have risen in recent years with at least 28,957 persons killed or injured by mines and ERW across 2019 – 2023 (Landmine & Cluster Munition Monitor, 2024a, b). Although the exact number of survivors is unknown, many develop subsequent long-term psychological and physical sequelae (Frost et al., 2017). The wider long-term effects of ERW are a social and economic burden to victims, their families, the wider at-risk community, and health systems (Frost et al., 2017).

For civilians and communities in war-affected countries, the presence of these weapons represents an ongoing threat. Many innocent civilians have lost life or limb by disturbing or inadvertently coming into contact with explosive remnants of war. These weapons can also hinder reconstruction efforts and threaten people’s livelihoods. Homes, hospitals and schools cannot be rebuilt – and contaminated land cannot be farmed – until such weapons are cleared (ICRC, no date).

Multi-hazard context

The figure below summarises common interactions between explosive ordnance and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.

Multi-hazard diagram

Risk Management

Protocol V of the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons outlines the following control measures to mitigate the impact of ERW: survey and assess the threat posed by ERW in a post-conflict situation; assess and prioritise needs for the marking and removal/clearance of ERW; and clear/remove the ERW where possible and safe (United Nations, 2004:3).

Monitoring

Established in 1997, the United Nations Mine Action Service (UNMAS) leads, coordinates, and implements projects and programmes to mitigate the threats posed by explosive ordnance to the benefit of millions of people worldwide. UNMAS provides Member States, the United Nations system and its leadership, as well as the mine sector at large, with authoritative, impartial expertise and experience acquired through its humanitarian, development, peace operations and peacebuilding assistance to affected countries, as well as through its participation in, and contributions to, treaty-related and diplomatic processes. Among its chief responsibilities and capabilities, UNMAS supports the development of standards, policies and norms as well as managing operations to clear landmines and explosive remnants of war (ERW) and mitigate the threats posed by improvised explosive devices (IEDs). In its broad sense, mine clearance, or 'demining', includes surveying, mapping and marking, as well as detecting and destroying mines, ERW and IEDs. (UNMAS, no date)