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Recently the U.S. accused the Taliban of using white phosphorus (WP) in improvised explosive devices (IEDs) in civilian areas in Afghanistan, as well as in mortar and rocket attacks against U.S. forces. The Taliban denied using or possessing WP munitions. For its part, the U.S. stated that both it and NATO’s International Security Assistance Force do not use WP munitions as an anti-personnel weapon in Afghanistan, and confirmed, in accordance with its earlier position, that it employs WP munitions only for purposes such as marking targets or igniting enemy ammunition. In 2005, however, the U.S. admitted, after first denying, that it used WP munitions against insurgents in “shake and bake” operations in Iraq in 2004. During such operations, WP munitions were used to flush out insurgents from spider holes at which point they were exposed to high-explosive ordinance.
Other recent conflicts in which the use of WP munitions has been documented or alleged include Somalia, Lebanon, Sri Lanka, and Gaza.
WP munitions may be advantageous in a military context due to the dense smoke produced when WP comes into contact with oxygen, as well as to the incendiary capacity of WP. During armed conflicts, the smoke produced by WP munitions has been used to mark targets, to screen troop positions, and to illuminate darkened areas. WP munitions have also been used in armed conflicts to destroy unoccupied bunkers and to ignite enemy ammunition. However, when ignited WP munitions come into contact with human flesh, they may burn through skin causing tremendous pain and tissue damage.
The alleged use of WP munitions, by both states and non-state actors such as the Taliban, is regulated in part by international humanitarian law (IHL). To determine whether a certain use of WP munitions in armed conflict is in conformity with IHL, it is necessary to assess pertinent treaties and customary law.
Overview of sources of law. Only states that have taken necessary and sufficient steps to become party to a treaty are bound by the obligations entailed in that treaty. A non-state armed group such as the Taliban cannot become a party to bilateral or multilateral treaties. However, Common Article 3 (CA3) of the four 1949 Geneva Conventions defines certain rules that apply to all parties in non-international armed conflicts. According to an International Court of Justice (ICJ) judgment, those rules constitute a minimum yardstick in international armed conflicts as well.
While non-state actors cannot become a party to international treaties, they may enter into special agreements. For instance, CA3 expressly provides that parties “to the conflict should endeavor to bring into force, by means of special agreements, all or part of the other provisions” of the Geneva Conventions. Similarly, Article 96(3) of Protocol I provides that non-state actors may undertake to comply with and bind themselves to the Geneva Conventions and Protocol I in certain types of conflicts, such as fights against colonial domination and alien occupation.
Another way non-state actors can undertake to comply with certain norms is through a “Deed of Commitment.” Geneva Call, an international humanitarian organization, has established a mechanism by which non-state actors can sign a Deed of Commitment to adhere to the norms embodied in the 1997 anti-personnel mine ban treaty. To date, 39 non-state actors have signed such deeds. The extent to which such deeds will be expanded to include other weapons, such as WP munitions, or modes of conduct is uncertain.
It is important to note that all parties to an armed conflict – whether state armed forces or non-state armed groups – are bound, at a minimum, by customary international law. As formulated in the ICJ’s statute, international custom consists of general state practice accepted as law. While non-state armed groups may not be bound by a treaty as such, many treaty provisions are reflective of customary international humanitarian law, and those provisions are thereby binding on all parties to a conflict.
Specific treaties. The Chemical Weapons Convention (CWC) is an international treaty to which 188 states are party. The CWC regulates the use of chemicals and chemical precursors as weapons. To fall under the CWC’s regulations, WP munitions would need to fulfill two cumulative conditions. First, they would need to constitute chemicals or chemical precursors as defined in the CWC. Second, they would need to be used for a proscribed purpose, such as for use as a weapon in armed conflict. The Organisation for the Prohibition of Chemical Weapons (OPCW) monitors implementation of the CWC. The OPCW’s spokesman has stated that the CWC does not prohibit the application of WP munitions when they are used to produce smoke or to camouflage movements. In such circumstances, the spokesman noted, the toxic properties of WP are not required or intended to be used.
However, according to the OPCW spokesman, the CWC prohibits the use of WP munitions where the toxic properties of WP are “specifically intended to be used as a weapon”. One scholar has formulated the pertinent question as, “[w]hether the harmful effects of fire and smoke produced by WP munitions constitute ‘chemical action on life processes’ in the CWC’s definition of a toxic chemical”. (The U.S. reportedly classified Iraq’s alleged anti-personnel use of WP munitions in 1991 as a chemical weapons attack.)
A Pentagon spokesman has stated that the U.S. used WP munitions as an “incendiary weapon against enemy combatants” in Iraq in 2004. The use of incendiary weapons is regulated in part by Protocol III of the Convention on Conventional Weapons (CCW), to which 103 states are party (though the U.S. was not a party to Protocol III until January 2009). Protocol III defines incendiary weapons as any weapon or munition that “is primarily designed to set fire to objects or to cause burn injury to persons”. Article 1(b)(i) expressly states that munitions “which may have incidental incendiary effects, such as illuminants, tracers, smoke or signalling systems” are not considered incendiary weapons for purposes of Protocol III.
The U.S. recently became a party to Protocol III. The U.S. registered a reservation and an understanding in doing so. The U.S. reservation stated in part that the U.S. “reserves the right to use incendiary weapons against military objectives located in concentrations of civilians where it is judged that such use would cause fewer casualties and/or less collateral damage than alternative weapons….”
By its terms, Protocol III prohibits, among other things, making civilians and civilians objects the object of attack by incendiary weapons in all circumstances; making any military objective located within a concentration of civilians an object of attack by incendiary weapons delivered by air; and making certain military objectives in civilian concentrations object of attack by non-air-delivered incendiary weapons without taking adequate precautions. As noted above, the U.S. admitted to using WP munitions as an “incendiary weapon against enemy combatants” in Iraq in 2004. Assessing whether such a use of WP munitions would comply with Protocol III would depend on determining whether WP is an incendiary weapon under the treaty definition, and if so, looking to the mode of delivery of WP munitions, whether the military objective was “clearly separated from the concentration of civilians,” and whether “all feasible precautions [were] taken with a view to limiting the incendiary effects to the military objective and to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects.”
Customary law. The rules in customary law regarding chemical weapons and incendiary weapons, insofar as those rules have been formulated by the International Committee of the Red Cross (ICRC), are similar to the relevant provisions in the CWC and in Protocol III of the CCW. The ICRC has stated that in both international armed conflicts and non-international armed conflicts, the use of chemical weapons is prohibited, and “[t]he 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.” When incendiary weapons are used, the ICRC stipulates, “particular care must be taken to avoid, and in any event to minimize, incidental loss of civilian life, injury to civilians and damage to civilian objects”. The U.S. reservation to Protocol III, as excerpted above, is largely reflective of these customary rules. In addition, it bears emphasis that more general rules of customary law also apply to the use of WP munitions. These include the rule that parties must always distinguish between, on one hand, civilians and civilian objects, and on the other, military objectives, and never target the former.