Indirect fire and precision guided munitions

States translate international standards into detailed rules, including on the use of explosive weapons, for the benefit of their armed forces.

Unfortunately, these standards are seldom accessible to the public.²¹³ Due

210 Note the reference to“the effects of the use of … certain blast and fragmentation weapons” in relation to the conviction “that the suffering of the civilian population and combatants could be significantly reduced if agreements can be attained on the prohibition or restriction for humanitarian reasons of the use of specific conventional weapons” expressed in Geneva Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law applicable in Armed Conflicts, 1974–1977, Follow up Regarding Prohibition or Restriction of Use of Certain Conventional Weapons, resolution 22, 9 June 1977.

211 See for example, UK Ministry of Defence, The Joint Service Manual of the Law of Armed Conflict, document JSP 383, 2004, para. 6.11; Program on Humanitarian Policy and Conflict Research at Harvard University, Commentary on the HPCR Manual on International Law Applicable to Air and Missile Warfare, 2010, pp. 75–77.

212 Protocol on Prohibitions or Restrictions on the Use of Incendiary Weapons (Protocol III to the CCW), 10 October 1980, art. 1(1)(ii).

213 “Too often national or multinational security classifications mean that the publication and sharing of rules of engagement experience and best practice

to the paucity of military regulations in the public domain, the Rules of Engagement Handbook published by the San Remo International Institute of Humanitarian Law is helpful to gain an idea of what national standards may look like.²¹⁴ The Handbook provides Rules of Engagement (ROE) options that may be tailored to specific missions and in many instances is no more specific than the rules of IHL.

In some cases, however, the Handbook proposes rules pertaining to the use of explosive weapons not mandated in these terms by IHL. This is the case of ROE on “indirect fire”. Indirect fire is defined as “fire directed at a target that cannot be seen by the aimer and that is not itself used as a point of aim for the weapons or the director”. The Handbook distinguishes between “observed indirect fire”—for which the point of impact or burst can be seen by an observer—and “unobserved indirect fire”—for which points of impact or burst are not observed. Direct fire and observed indirect fire is permitted unless restricted by a rule. Noteworthy is that the proposed ROE refers to a prohibition in “populated areas”. Unobserved indirect fire is presumed prohibited, unless authorized by a rule specifying exceptional circumstances.²¹⁵ Use of the term “burst” in this context indicates that indirect fire is about weapons that explode, but the notion

is problematic. The ability for militaries to share their experiences as well as for academics, students and the public to consider the subject is critical in order to promote awareness of the practical implementation of International Humanitarian Law through rules of engagement”. International Institute of Humanitarian Law, Rules of Engagement Handbook, November 2009, p. ii.

Belgium and Switzerland for example do not have a military manual. The French Ministry of Defence has published its Manuel de droit des conflits armés, 2001, but its content does not provide information as to the use of explosive weapons beyond the rules of IHL. UK Ministry of Defence, The Joint Service Manual of the Law of Armed Conflict, document JSP 383, 2004, para. 6.4.1, is slightly more specific. For example, it identifies “V1 flying bombs” used in the Second World War and “Scud rockets” used during the Gulf conflict of 1990–1991 as examples of weapons likely to be indiscriminate weapons.

214 International Institute of Humanitarian Law, Rules of Engagement Handbook, November 2009. The Handbook is meant to assist in the drafting of Rules of Engagement (ROE), standards issued by competent authorities to, inter alia, authorize or limit the use of force by military forces. ROE may be more restrictive, but never more permissive, than applicable national and international legal standards.

215 Ibid., pp. 37, 82, 84-85.

of indirect fire focuses on a mode of delivery rather than on blast and fragmentation effects.

Blast and fragmentation effects are an explicit consideration in some US regulations, but explosive weapons are nevertheless subject to differential treatment in function of their mode of delivery. US Joint Chiefs of Staff Instruction CJCSI 3106.01 (2009), for example, documents the Department of Defense’s policy governing the “collateral damage estimation … methodology (CDM)”, which describes a process that involves the assessment of the probability of civilians in the vicinity of the target suffering “serious/lethal wounds” from “primary warhead fragmentation or debris” and of structures being damaged by blast effects.²¹⁶ It is interesting to note that although the assessment process “accounts for all conventional munitions currently in the U.S. inventory”, no estimation is required for

“surface-to-surface direct fire weapon systems”, including 120mm cannon and “rotary wing or fixed-wing air-to-surface direct fire weapon systems less than 105mm”, including 2.75in rockets. The exclusion is justified on the basis that “The risk of collateral damage from these weapon systems is presented by the distribution of munitions in the target area and not from the explosive effects of the warhead”.²¹⁷

Similar differences among explosive weapons are based on the launching platform and the accuracy of delivery. The San Remo Handbook proposes special ROE to regulate use of air-to-surface munitions. One of the rules permits use of “precision-guided air to surface munitions” in specified areas. In contrast, “Use of non-precision air to surface munitions” is either

216 US Chairman of the Joint Chiefs of Staff, No-Strike and the Collateral Damage Estimation Methodology, document CJCSI 3160.01, 13 February 2009, p. D-A-1. Note that the CDM assumes that people in structures are predominantly injured or killed by blunt trauma from structural collapse and secondary debris. Although recognizing that “blast induced debris has been operationally observed to be a significant hazard to noncombatant personnel”, the “effects of blast induced debris have not been characterized” (ibid., p. D-A-2).

217 Ibid., p. D-4. Similarly, under UK Ministry of Defence, The Joint Service Manual of the Law of Armed Conflict, document JSP 383, 2004, para. 5.32.4, a

“direct fire weapon” (such as a wire-guided anti-tank missile) is considered less likely to cause incidental damage than indirect fire weapons (such as mortar or artillery rounds).

completely prohibited or is prohibited in specified areas.²¹⁸ Likewise, the US CDM applies different standards to “precision-guided munitions”

than to “air-to-surface unguided munitions” and “surface-to-surface ballistic munitions”, notably on the basis that the increased delivery errors associated with the latter two kinds of weapon systems present a higher risk of collateral damage than precision-guided munitions.²¹⁹ National military regulations in this issue area, it would seem, tend to categorize weapons in ways that are not necessarily based on international standards and that cut across weapons with similar blast and fragmentation effects.