ERW (Explosive Remnants of War)

Explosive Remnants of War (ERW) is a legal term of art covering two main categories of munitions left over from armed conflict: unexploded ordnance (UXO) — items that were fired, dropped, or otherwise deployed but failed to detonate as intended — and abandoned explosive ordnance (AXO) — munitions left behind by a party to a conflict without being used, often in caches or depots no longer under any actor's control. Common examples include artillery shells, mortar bombs, grenades, aircraft bombs, rockets, and submunitions from cluster weapons.

The category is formally defined in Protocol V to the Convention on Certain Conventional Weapons (CCW), adopted in Geneva on 28 November 2003 and entering into force on 12 November 2006. Protocol V was the first multilateral instrument to address ERW comprehensively as a post-conflict humanitarian problem. It places obligations on parties to a conflict to mark, clear, remove, or destroy ERW in territory under their control after hostilities end, to record and share information on the ordnance they used to facilitate clearance, and to provide risk education to affected civilian populations.

Notably, anti-personnel landmines are not ERW under Protocol V — they are governed separately by the Ottawa Convention (1997) and CCW Amended Protocol II. Cluster munition remnants overlap heavily with ERW and are additionally regulated by the Convention on Cluster Munitions (2008).

ERW continues to cause civilian casualties for decades after wars end. Heavily contaminated countries include Cambodia, Laos, Vietnam, Afghanistan, Iraq, Syria, Ukraine, Bosnia and Herzegovina, and Angola. Clearance is typically conducted by national mine action centres alongside operators such as HALO Trust, MAG (Mines Advisory Group), Norwegian People's Aid, and the UN Mine Action Service (UNMAS). ERW is also a significant obstacle to post-conflict reconstruction, agricultural recovery, refugee return, and infrastructure rehabilitation.