They located and defused 4,622 pieces of unexploded ordnance. Abandoned booby traps and discarded grenades contribute to the problem of unexploded ordnance (UXO). Some areas are still under the threat of unexploded ordnance. Robots are used to perform remote procedures on unexploded ordnance and improvised explosive devices. Military uses include detection of mines, unexploded ordnance, and tunnels. Today, the ground is littered with discarded bullet cases and unexploded ordnance. Amatol is rare today, except in legacy munitions or unexploded ordnance. Military applications of ground-penetrating radar include detection of unexploded ordnance and detecting tunnels. Many more were assigned to construction units repairing railroads and airfields and disposing unexploded ordnance. They preferred to make IEDs from Soviet unexploded ordnance. Unexploded ordnance, however old, may explode. Aeromagnetic surveys are also used to perform reconnaissance mapping of unexploded ordnance. They were commonly constructed using materials from unexploded American ordnance. I ATACMS missiles to eliminate the risk of unexploded ordnance by 2016. The Ottawa Treaty does not cover all types of unexploded ordnance.