Incendiary weapon delivery systems include bombs, rockets, shells, grenades, bullets, flamethrowers, and land-mines. These are used to carry the incendiary agents that affect their targets primarily through the action of heat and flame derived from self-propagating exothermic chemical reactions. They include: petroleum-based incendiaries such as napalm compositions; metal incendiaries such as magnesium, pyrotechnic incendiaries such as white phosphorus; and certain organometallic compounds which ignite spontaneously in air. Such weapons are capable of causing massive destruction to both the rural and urban environment. Such destruction is often unavoidably and even deliberately indiscriminate, and may be particularly detrimental to the civilian rather than the military component of a society. Incendiary warfare is particularly cruel in its effects, notably because of the long period of recovery required for survivors and the high probability of permanent deformity with consequent emotional disorders. The relatively low cost of incendiary weapons adds to the danger, since they are available to even the poorest countries.
Napalm kills not only by burning but by asphyxiating or poisoning its victims. Its adhesiveness, high burning temperature, and prolonged burning time lead to deep burns. As napalm is scattered over target areas in large clumps, victims are usually struck by a substantial mass of it; by attempting to remove the napalm from the skin, or strip off their burning clothes, they spread it over other parts of their bodies, particularly their hands. Napalm often causes not only third but fourth and fifth-degree burns, which completely char the skin and extend into the deep tissue of the body, damaging muscles and reaching even to the bones and internal organs. For adequate medical treatment of burn casualties, vast facilities would be required to meet the emergencies caused by large-scale attacks. It has been estimated that to treat 1,000 wartime casualties having 30% burns, the following would be needed: 8,000 litres of plasma, 6,000 litres of blood, 16,000 litres of a balanced salt (lactate) solution, 250 trained surgeons and physicians, approximately 1,500 skilled attendants, and hospital beds for each patient for up to four or five months. Even in the developed countries, such requirements would be difficult to mobilize on any scale; in the developing countries it would be virtually impossible.
Most incendiary bombs used in the Second World War consisted mainly of magnesium or thermite (a mixture of ferric oxide and aluminium). Incendiaries were extensively used in German raids against London, 1940 causing 600 deaths, by the RAF against Hamburg in 1943 causing 50,000 deaths, and Dresden in 1945 causing 80,000 to 135,000 deaths, and by the USA Armed Forces against Tokyo in 1945 causing 83,000 deaths. During the Korean War over 32,000 tons of napalm were used and during the Vietnam War more than 100,000 tons had been dropped by March 1968.
While it may sometimes be convenient to classify incendiary agents as a separate category of weapons, they are capable of acting in ways similar to chemical weapons and therefore should be treated as such by international conventions limited to chemical-biological weapons.