Joint forces should be prepared to encounter barriers, obstacles (including improvised explosive devices IEDs], mines, and other unexploded explosive ordnance UXO]) and to conduct mine warfare (MW), employing mines on land and sea across the range of military operations. Employing and countering obstacles differ on land and at sea. For example, while obstacles on land are primarily employed and countered by combat engineers, this is not the case at sea, where ships, aircraft, and underwater elements deploy and/or counter obstacles, naval mines, and IEDs.