Explosive remnants of war (ERW) are explosive munitions left behind after a conflict has ended. They include unexploded artillery shells, grenades, mortars, rockets, air-dropped bombs, and cluster munitions. Under the international legal definition, ERW consist of unexploded ordnance (UXO) and abandoned explosive ordnance (AXO), but not mines.
Weapons that fail to detonate as intended become unexploded ordnance (UXO). These unstable explosive devices are left behind during and after conflicts and pose dangers similar to landmines.
Abandoned Explosive Ordnance
Abandoned explosive ordnance (AXO) is explosive ordnance that has not been used during armed conflict and has been left behind and is no longer under control of the party that left it behind. It may or may not have been primed, fuzed, armed, or otherwise prepared for use.