Rule 85. The anti-personnel use of incendiary weapons is prohibited, unless it is not feasible to use a less harmful weapon to render a person hors de combat.
Volume II, Chapter 30, Section B.
State practice establishes this rule as a norm of customary international law applicable in both international and non-international armed conflicts.
During the discussions in the 1970s, many States were in favour of a total prohibition of the use of incendiary weapons, including against combatants.
Official statements supporting a total ban were also made by a number of States.
The legislation of several States prohibits the use of incendiary weapons altogether.
In 1972, the UN General Assembly adopted a resolution on general and complete disarmament in which it deplored the use of napalm and other incendiary weapons in all armed conflicts.
When it became clear, however, that a total prohibition would not command consensus at the Preparatory Conference for the Convention on Certain Conventional Weapons, a number of States tried, as a fall-back position, to achieve a prohibition of their use against combatants with limited exceptions, such as when they were under armoured protection or in field fortifications.
However, this was still opposed by a few States, in particular the United States and to some degree the United Kingdom.
Since Protocol III to the Convention on Certain Conventional Weapons was to be adopted by consensus, this prohibition was not included in the Protocol. The fact that this prohibition was not included in the Protocol does not mean, however, that the use of incendiary weapons against combatants is lawful in all circumstances.
Several States have specified the few restricted situations in which incendiary weapons may be used, namely when combatants are under armoured protection or in field fortifications.
Others have stated that incendiary weapons may not be used in a way that would cause unnecessary suffering.
Several military manuals and a number of official statements make the point that the use of incendiary weapons against combatants is prohibited because it causes unnecessary suffering.
There are very few reports of use of napalm and similar incendiary weapons against combatants since the adoption of the Convention on Certain Conventional Weapons. What reports there are have been in the form of accusations condemning their use and are unconfirmed.
It can be concluded from this practice that incendiary weapons may not be used against combatants if such use would cause unnecessary suffering, i.e., if it is feasible to use a less harmful weapon to render a combatant hors de combat
The situation with respect to non-international armed conflicts is similar to that described under the previous rule, namely that there has been no particular need for the international community to address the issue in the last 20 years. It is nevertheless reasonable to conclude that the rule is applicable in non-international armed conflicts. As it is prohibited in non-international armed conflicts to use means and methods of warfare of a nature to cause unnecessary suffering (see Rule 70), the anti-personnel use of incendiary weapons in situations where such use is not required by military necessity would constitute a violation of that rule.