Also known as UXO, un
exploded
ordnance is all of the aircraft
bombs,
artillery shells,
anti-tank rockets, and other various explosive weapons that didn't go off when they were intended to. Whereas
land mines (which are not generally considered UXO, although UXO specialists are still called
deminers) are meant to lie in wait until accidentally triggered, UXO is ordnance that was meant to explode and kill or do damage, but didn't. Areas that have been involved in modern
land wars often have thousands of tons of UXO
littering any area that looked juicy enough to bomb by an aggressor: roads, industrial areas, farmland, etc.
Laos,
Vietnam, and
Lebanon have lots of publicity about their UXO problems; in ten years much of
Eastern Europe probably will too.
Laos was bombed by the United States between 1964 and 1973, specifically the Ho Chi Minh Trail that functioned as a supply line for North Vietnam. An average of one planeload of bombs every eight minutes (about 2 million tons total) were dropped, and bomb manufacturers estimate that between 20 and 30 percent of the bombs didn't explode. Twenty years later, in 1995, the UN set up a $12 million trust fund for UXO clearance, which was used to set up the UXO Lao program by the Laos government. UXO Lao educates villages about unexploded ordnance, teaching children and adults how to avoid UXO or move it safely.
UXO Lao also does controlled detonation, in hope of eventually ridding the country of all unexploded ordnance. The less-preferred way of UXO removal is known as a high-order explosion, in which the bomb's own detonating mechanisms are used to explode it. This method is dangerous for the team, as it forces them to force the bomb's detonation and thus potentially detonate it on accident. This also looses the bomb's full power, so it must be done far away from people, and the deminers to work far away from the ordnance.
When possible, a low-order explosion is used instead. A low-order explosion is one in which the explosive materials inside of the bomb are deflagrated, but not detonated. That is, the explosive may burn off with force, but it isn't allowed to cause the shockwave chain reaction that would increase it's force by an order of magnitude in a true detonation. Humorously, the device used to cause a low-order explosion is called a baldrick, after a character from the BBC Blackadder show who often suggested blowing something up to solve a problem. Ideally, a baldrick will have some way of penetrating the bomb, possibly a rod or plate that is shot out upon firing. Then the propellant itself -- an incendiary of some kind -- will enter the bomb through that hole, setting the bomb's explosive contents on fire.