War Crimes and the Use of Improvised and Indiscriminate Weapons in Syria

Editor’s note: This is the latest in a continuing series about alleged war crimes in Syria. You can find the previous installments here and here.

While several sides of the conflict in Syria have temporarily set aside their weapons (albeit imperfectly) and with peace talks scheduled to restart tomorrow (or maybe next week), this seems like an opportune time to look at some of the weapons that have been used and the law governing munitions as part of my ongoing series about alleged war crimes in the country. This post discusses deliberate, indiscriminate, and disproportionate attacks on civilians carried out with specific weaponry, and looks at when the use of certain weapons or weapon systems can constitute war crimes under international law, even when used against combatants, who are lawful targets.

As an initial matter (and as I have discussed previously), although determining what sort of conflict is at issue remains an important exercise, it has become less relevant to the prosecution of war crimes since the renaissance of customary international law (CIL) in international criminal law. Customary international law now prohibits and penalizes many breaches of international humanitarian law (IHL) regardless of whether they are committed in an international armed conflict (i.e., a conflict between states, or IAC) or a non-international conflict (i.e., a conflict between a state and non-state actors or among non-state actors, also known as a NIAC). Thus, a tribunal dedicated to the conflict in Syria (and/or Iraq) could prosecute most war crimes without running afoul of the international law principle that prohibits the prosecution of anyone for an act that was not criminal at the time it was committed. However, it’s worth noting that if an ICC referral is ever forthcoming, there are some war crimes for which the IAC/NIAC distinction remains relevant under Article 8 of the ICC Statute. Additionally if the only courts available to prosecute war crimes in Syria are domestic courts, individual states may not have codified the full range of war crimes with respect to NIACs, particularly when it comes to prohibited and problematic weaponry. The law in this area thus exemplifies two of the themes of this series: There are times when activities that are clearly war crimes cannot be prosecuted because appropriate courts cannot be found, and there are times when the law isn’t sufficiently clear to allow a prosecution to move forward. These issues come into stark relief in the context of the specific weapons and weapon systems used in Syria.

Deliberate, Indiscriminate, and Disproportionate Attacks on Civilians

One of the foundational IHL principles requires all parties to a conflict to distinguish between lawful and unlawful targets, and this distinction underlies a number of war crimes (e.g., here, here, and here). The law governing the direct targeting or mistreatment of civilians, civilian objects, and other protected persons and things is relatively straightforward and applies across the conflict spectrum. These prohibitions could open the door to prosecuting those responsible for deliberate attacks on bakeries and markets in opposition-controlled territory and the mistreatment of civilians, combatants, and other armed actors in formal and informal detention facilities. These rules would also enable the prosecution of those who deliberately target journalists or hospitals, which enjoy special protection under IHL. (Russia has also been implicated in intentional hospital attacks.) All these crimes could easily be prosecuted by the ICC or under most domestic war crimes statutes (assuming the latter penalized such crimes when committed in NIACs).

Beyond such direct attacks, however, the ICC Statute diverges from CIL and depends in meaningful ways on conflict classification. National penal codes that hew closely to IHL treaties will do the same. As a result, prosecuting even obvious war crimes in the Syrian context may be quite complex. For example, the ICC cannot prosecute the crime of deliberately inflicting terror on a civilian population, even though this crime has a strong treaty basis in both IACs and NIACs, as well as in CIL. A tribunal with jurisdiction over CIL war crimes (rather than the ICC), however, could prosecute this offense in connection with events in Syria.

This dual bifurcation between treaty law and CIL, and between IACs and NIACs, is also apparent when it comes to the penal law governing indiscriminate or disproportionate attacks. The former involves attacks that are not directed at a specific military objective, that involve a method or means of warfare that cannot be directed at a military objective, or whose effects cannot be limited. The prohibition against area bombardment, applicable under CIL in both IACs and NIACs, is a distinct subset of indiscriminate attack. This prohibition is implicated by recent presidential campaign calls to “carpet bomb” ISIL.

Disproportionate attacks, on the other hand, are those that generate “incidental loss of civilian life and damage to civilian objects [that is] excessive in relation to the concrete and direct military advantage anticipated.” The ICC Statute allows disproportionate attacks to be prosecuted only when committed in an IAC. Of even greater import for events in Syria, the ICC Statute contains no provision criminalizing indiscriminate attacks at all — regardless of conflict classification. As such, when it comes to NIACs, the ICC Office of the Prosecutor can only charge intentional attacks on civilians and civilian objects. These gaps in the ICC regime have implications for a range of crimes being committed in Syria involving unconventional, improvised, and prohibited weapons and weapon systems.

Unconventional and Improvised Weapons and Weapon Systems

The warring parties in Syria have deployed a number of munitions that — by design or how they’re used — are incapable of distinguishing between civilians and combatants, or between civilian objects and military objectives. In addition, some munitions in use are per se prohibited, even when deployed against combatants who are normally susceptible to direct attack. IHL is premised on the idea that the means and methods of warfare are not without limit. For example, in all conflicts, IHL bans the use of weapons and other methods of warfare that cannot adhere to the principle of distinction or that by their nature cause superfluous injury or unnecessary suffering.

IHL also reflects more pointed prohibitions against the use of particular weapons and weapon systems, though these bans are often contained in treaties dealing with disarmament rather than criminal penalties for use. As a result, prosecutions must proceed under either CIL or more general IHL prohibitions like those discussed above (i.e., a prosecutor will not charge the defendant with using an improper weapon per se but rather with launching an attack with a weapon that caused indiscriminate or disproportionate harm to civilians). Because those crimes are not included in the ICC Statute in NIACs, it would be harder for the ICC to prosecute the rampant use of unconventional and improvised weapon systems in Syria absent evidence that civilians were directly targeted. Other tribunals may or may not face the same difficulties, depending on their specific mandates.

Barrel Bombs

The Assad regime’s barrages of barrel bombs have come to represent the brutality of the regime. These improvised containers are generally filled with bulk explosives, incendiaries, and fragmentation media, and then dropped from helicopters and other aircraft. There are also indications that chemical agents (e.g., chlorine) have been included within the encasements and that their release has been sequenced in such a way as to maximize the impact on first responders. The Assad regime has consistently disavowed their use, but recovered cell phone videos have disproved these denials.

Although there is no CIL rule governing barrel bombs per se, the UN Commission of Inquiry in Syria invoked the customary prohibition against indiscriminate attacks, and specifically the ban on area bombardment, to condemn their use in Syria. The use of barrel bombs has also generated widespread criticism in both the UN Security Council and the General Assembly. In the Secretary-General’s 21st report on the implementation of the Security Council’s resolutions aimed at curbing IHL abuses in Syria, he concluded that indiscriminate attacks, including the use of barrel bombs, remain prevalent despite Syrian assurances to the contrary. Indeed, the Council later voiced “grave alarm in particular at the continuing indiscriminate attacks in populated areas, including an intensified campaign of aerial bombings and the use of barrel bombs in Aleppo and other areas.” Notwithstanding these denunciations, the attacks continue.

Although barrel bombs may be an Assad innovation, there is some relevant legal precedent attesting to their illegality. In 2009, the International Criminal Tribunal for the former Yugoslavia found Dragomir Milošević guilty of spreading terror among the civilian population based on his ordering the use of “modified air bombs” against civilians during the siege of Sarajevo. The ICTY noted these were “a highly inaccurate weapon, sometimes even described as uncontrollable, yet with extremely high explosive force.” On appeal, the ICTY confirmed that the actual infliction of death or serious bodily harm is not a required element of the crime of inflicting terror on the civilian population; what matters is that the defendant act with the intent to spread terror. The same legal standard may apply to the Assad regime’s actions in Syria.

Cluster Munitions

Cluster munitions have been air-dropped and ground-launched by Syrian forces (since mid-2012) and by ISIL (since late 2014) in multiple opposition-controlled locations around Syria, killing hundreds of civilians. Human Rights Watch has recorded the use of advanced Russian-made cluster munitions following Russia’s September 2015 intervention, suggesting Russia is either using cluster munitions itself or is providing them to its allies. There is no indication that the US-led coalition has resorted to the use of cluster munitions, although the United States has used them — not without controversy — in previous contexts (e.g., Operation Allied Force in Kosovo in 1999 and Operation Iraqi Freedom in 2003).

Cluster munitions eject a payload of sub-munitions (bomblets or other fragmentation elements) from a dispenser upon contact or at a preset altitude. They are combined effect munitions (i.e., their payload may exert anti-material, anti-armor, anti-personnel, and incendiary effects). When unguided, as most in Syria are, cluster munitions are fairly inaccurate. Even when guided by the addition of a tail kit, they can generate a wide lethal radius because they are designed to distribute their sub-munitions over a large footprint, particularly when fired from a distance or higher altitudes. Cluster munitions are meant for wide-area targeting, and may be deployed against moving “soft” targets (enemy personnel and civilians) or to destroy runways, scatter landmines, penetrate armor, start fires, or deliver chemical weapons. Among other concerns, much of the payload may not detonate immediately and may lead to harm for many years after initial use.

There is no international consensus on whether the use of cluster munitions is per se unlawful under IHL, although some states, academics, and activists have argued it is and the law is certainly moving in that direction. Over 100 states, including many coalition partners in Syria and Iraq, have joined the 2008 Convention on Cluster Munitions (CCM) in recent years. But the United States, which possesses a large cluster munition stockpile, stands as a persistent objector to any per se prohibition on the use of cluster munitions, and a recent declaration at the First Review Conference on the CCM condemning “any use of cluster munitions by any actor” garnered strong, but not universal, support. A number of states — CCM parties and non-parties alike — have denounced the use of cluster munitions in Syria (e.g., here and here). Exemplifying the divide on the legality of their use, the ICRC’s CIL Study demurs and simply lists them as among the weapons that many states consider to be indiscriminate in certain or all contexts.

Regardless and even absent a universal treaty or CIL ban, the deliberate, indiscriminate, or disproportionate use of cluster bombs against civilians implicates many generalized prohibitions under IHL (e.g., here and here). For example, prior to the promulgation of the CCM, the ICTY held that use of cluster munitions in a “densely populated” area of Zagreb was presumptively unlawful under general IHL principles, even though there were military targets in the vicinity of the attacks. (The attack was also deemed a crime against humanity.) But, there may be certain scenarios where the use of cluster munitions against purely military objectives and far from any civilian population remains lawful. As a result, any war crimes prosecutions for the use of cluster munitions in Syria would likely be quite fact-bound.

Air-Dropped Incendiary Weapons

Use of air-dropped incendiary weapons, including so-called vacuum bombs or fuel-air explosives (FAEs), have also been recorded in Syria. FAEs are thermobaric weapons that disperse an aerosolized explosive cloud — often toxic on its own — ignited by a charge, producing an enormous shockwave. When these weapons are deployed sequentially, the resulting blast waves reinforce each other. Such weapons were developed primarily to deal with concealed targets (e.g., combatants hiding in bunkers who would be protected by shrapnel and debris). They are more powerful in terms of energy output, and thus more destructive, than conventional explosives. They also rely on multiple kill mechanisms: Those persons in the immediate vicinity are ignited or crushed by collapsing structures while those farther from the blast site die when their lungs or other internal organs rupture. Given their dispersed effects, it is extremely difficult to use such weapons discriminately in an urban or populated area; civilians simply can’t effectively take shelter.

The use of such weapons in Syria has been widely condemned. The Convention on Certain Conventional Weapons (which has been amended to apply to NIACs) and its Third Protocol ban the use of all incendiary weapons against civilians and air-delivered incendiary weapons in areas with “concentrations of civilians.” The ban exists even if there is a military objective in the area, unless this target is clearly separated, the weapon is land-delivered, and other precautions are taken. Additionally, CIL contains a qualified ban on such weapons in all conflicts, indicating that they can only be used as a last resort.

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In the absence of a specific prohibition, the improper use of these inherently imprecise weapons would ordinarily be charged as an indiscriminate attack or as launching an attack with the purpose of inflicting terror among the civilian population. However, their use within urban or densely populated areas — as we’ve seen in Syria — could also be charged as an intentional attack on civilians, even if some percentage of such weapons struck proper military objectives. If the harm to civilians is sufficiently acute, an indiscriminate attack could thus be regarded as the equivalent of a direct attack, which would be prosecutable before the ICC and most domestic courts with war crimes jurisdiction. If the international community, or a regional body, ever builds an ad hoc tribunal dedicated to this conflict, the juridical architects would enjoy greater license to expand the list of prosecutable war crimes to better reflect violations on the ground. 

About the Author(s)

Beth Van Schaack

Fellow at the Center for Advanced Study in the Behavioral Sciences (CASBS) at Stanford University, Former Leah Kaplan Visiting Professor of Human Rights at Stanford Law School, Former Professor of Law at Santa Clara University School of Law, Former Deputy to the U.S. Ambassador-at-Large for War Crimes Issues in the U.S. State Department All views are her own. Follow her on Twitter (@BethVanSchaack).