II. Applicable International Humanitarian Law
International Humanitarian Law
International humanitarian law, also known as the laws of war, applies to the armed conflict in Syria. The law applicable to the fighting in Syria, a non-international (internal) armed conflict, includes article 3 common to the four Geneva Conventions of 1949 (Common Article 3), and customary international humanitarian law.
The fundamental tenets of international humanitarian law are civilian immunity and distinction. While humanitarian law recognizes that some civilian casualties are inevitable, it imposes a duty on warring parties at all times to distinguish between combatants and civilians, and to target only combatants and other military objectives.
Civilian objects are those that are not considered military objectives. Military objectives are combatants, including civilians directly participating in the hostilities, and those objects that “by their nature, location, purpose or use, make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage.” In general, the law prohibits direct attacks against what are by their nature civilian objects, such as homes and apartments, places of worship, hospitals, schools, or cultural monuments, unless they are being used for military purposes.
Deliberate, indiscriminate, or disproportionate attacks against civilians and civilian objects are prohibited. Attacks are indiscriminate when they are not directed at a specific military objective, or employ a method or means of warfare that cannot be directed at a military objective or whose effects cannot be limited.
A disproportionate attack is one in which the expected incidental loss of civilian life and damage to civilian objects would be excessive in relation to the concrete and direct military advantage anticipated. The expected danger to the civilian population and civilian objects depends on various factors, including their location (possibly within or near a military objective), the accuracy of the weapons used (depending on the trajectory, the range, environmental factors, the ammunition used, etc.), and the technical skill of the combatants (which can entail random launching of weapons when combatants lack the ability to aim effectively at the intended target).
In the conduct of military operations, parties to a conflict must take constant care to spare the civilian population and civilian objects from the effects of hostilities. Parties are required to take precautionary measures with a view to avoiding, and in any event minimizing, incidental loss of civilian life, injury to civilians, and damage to civilian objects.
Before conducting an attack, a party to the conflict must do everything feasible to verify that the persons or objects to be attacked are military objectives and not civilians or civilian objects. Discussing Protocol I in its Commentaryon the Additional Protocols, the International Committee of the Red Cross (ICRC) explains that the requirement to take all “feasible” precautions means, among other things, that those conducting an attack are required to take the steps needed to identify the target as a legitimate military objective “in good time to spare the population as far as possible.”They also must take all feasible precautions in the choice of means and methods of warfare to minimize loss of civilian life and property.
International humanitarian law does not prohibit fighting in urban areas, although the presence of civilians places greater obligations on warring parties to take steps to minimize harm to civilians. Forces must avoid locating military objectives within or near densely populated areas, and endeavor to remove civilians from the vicinity of military objectives.Belligerents are also prohibited from using civilians to shield military objectives or operations from attack. "Shielding" refers to purposefully using the presence of civilians to render military forces or areas immune from attack. The unlawful deployment of forces within or near densely populated civilian areas does not relieve opposing forces from taking into account the risk to civilians when conducting attacks. The obligation to respect international humanitarian law does not depend on reciprocity by belligerent forces.
Individuals who commit serious violations of international humanitarian law with criminal intent are responsible for war crimes. Criminal intent has been defined as violations committed intentionally or recklessly.  Individuals may also be held criminally liable for attempting to commit a war crime, as well as assisting in, facilitating, aiding, or abetting a war crime. Responsibility may also fall on persons planning or instigating the commission of a war crime.  Military commanders and civilian leaders may also bear personal responsibility as a matter of command responsibility if they knew or should have known about the commission of war crimes and failed to prevent them or punish those responsible.
Those acts considered to be war crimes can be found in customary law as reflected in the Rome Statute of the International Criminal Court (ICC) and other sources. They include a wide array of offenses, including mistreatment of persons in custody, and deliberate, indiscriminate, and disproportionate attacks harming civilians. When committed as part of a widespread or systematic attack against a civilian population, such offenses constitute crimes against humanity.
Other relevant laws-of-war issues, including attacks on hospitals and the use of cluster munitions and incendiary weapons are discussed in the relevant sections, below.
Unlawful Air Strikes
As noted above, deliberate attacks on civilians are war crimes. Indiscriminate (and disproportionate) attacks carried out with criminal intent are also war crimes. The frequency of government air strikes in Syria that have struck only civilians and civilian objects with high-explosive munitions in populated areas indicates that those ordering the air strikes have been acting deliberately or recklessly.
Additionally, the repeated indiscriminate air strikes carried out by Syrian government forces suggests command responsibility for such attacks. That is, there are Syrian commanding officers who knew or should have known about the unlawful attacks and were legally obligated to take action to deter them or punish those responsible, but failed to do so. 
The rebel Free Syrian Army (FSA) themselves have unlawfully contributed to civilian casualties by deploying headquarters and other military objectives in densely populated areas. However, such deployments do not give license to the Syrian government forces to conduct unlawful attacks. In none of the cases documented by Human Rights Watch have Syrian forces given advance warnings of the attacks.
All of the attacks documented in this report appear to have been carried out with unguided munitions dropped without precision by jets and helicopters.The Syrian Air Force does not have guided munitions in its arsenal. Unexploded munitions and munitions identified by their remnants by Human Rights Watch weapons experts were all unguided.
Striking a specific military target with unguided air-to-surface munitions is challenging, according to military experts, as successful targeting depends on a combination of factors: the qualifications and experience of the pilot, availability of equipment that would allow the pilot to distinguish the target from nearby civilian objects, good visibility, proper attack angle, elevation, and speed, to name a few. The ICRC has stated that the use of “weapons which by their nature are incapable of being directed with any certainty to specific military targets, or which in their typical or normal use are not delivered with any certainty to such targets,” are in violation of the principle that parties to an armed conflict must ensure that civilians and civilian objects are respected and protected.
Human Rights Watch investigations found very few Syrian government air strikes that struck FSA military targets, whether FSA fighters or static military objectives. The means (munitions) and methods (bombing by jet fighters and other aircraft) of attack on FSA military targets in various cities investigated by Human Rights Watch raise grave concerns that these air strikes could never adequately distinguish between combatants and civilians.
In addition to standard unguided munitions, the Syrian armed forces have produced and used in civilian areas improvised munitions, “barrel bombs,” made from metal objects such as gas cylinders, oil barrels, and even a folded-up door, which contain a mixture of bulk explosive and fragmentation media (nails, cut up steel rebar, etc). These improvised bombs are mated with a simple timing device, and are then pushed out of a helicopter into a target area.
Syrian forces have used these improvised bombs in an indiscriminate manner, as evidenced by a video posted on YouTube. A soldier is seen using a cigarette to light a fuse on an improvised munition and pushing it out the back of the helicopter that is clearly flying at such a high altitude that it could not hit a target in a populated area with any precision.
In most of the air strikes investigated by Human Rights Watch, as well as dozens of other attacks videotaped and reported by Syrian activists, Human Rights Watch’s analysis of damage and munitions remnants showed that Syrian forces used large, high-explosive weapons. Destruction from such weapons can be so extensive in highly populated areas that even attacks that hit a military objective will still cause indiscriminate or disproportionate harm to civilians and civilian property.
Human Rights Watch found the use in towns of OFAB 250-270 unguided, high-explosive bombs, which can cause injury to people in a 155-meter radius from where it strikes.
In some cases, such as the August 15 attack on Azaz, a small town near the Turkish border, and the December 14 attack on Kansba in Latakia, the damage from the attack was so extensive that it likely resulted from a bomb larger than the OFAB 250-270 or several bombs exploding at the same time, according to Human Rights Watch military experts who reviewed photos of the damage.
Even though Human Rights Watch itself has not documented remnants of bombs larger than the 250-kilogram sized weapons like the OFAB-250-270, videos posted on YouTube show that the government has used larger bombs in populated areas, such as fuel-air explosives (FAEs), popularly known as “vacuum bombs,” which are more powerful than conventional high-explosive munitions of comparable size, and more likely to kill and injure people over a wide area. Eliot Higgins, a well-known and widely cited independent arms expert blogging under the name of “Brown Moses”, has collected videos and analyzed 14 instances of FAE use—most of them in populated areas.
The use of high-explosive weapons in populated areas is not specifically prohibited by international law, although it has been argued that their use in populated areas should be limited or banned altogether given the likelihood of harm to the civilian population. As a matter of policy, Human Rights Watch has called for a halt to the use of explosive weapons with wide area effects in populated areas as being inherently indiscriminate. The UN secretary-general and the ICRC have made similar calls.
The Syrian government rarely issues statements or comments on air strikes. In the few cases when it has done so, the statements have been general and vague, referring to attacks on “terrorists” and destruction of “terrorist headquarters” without providing any further information or details that would lend insight into the legality of the attack. Where it was possible to match government statements with cases that we documented, Human Rights Watch found no evidence supporting the government claims, such as losses to FSA fighters or damage to FSA deployments.
For example, on August 31, Syria’s state-run news agency, SANA, reported that “armed forces carried out an operation in which five terrorist headquarters were destroyed” in al-Bab. But according to local residents interviewed by Human Rights Watch, none of the strikes on August 31 hit buildings used by the FSA. Instead, the Syrian Air Force struck three schools, none of which were used by the FSA. One strike hit two residential houses, killing four civilians. Another strike hit another residential home, but resulted in no casualties because the family was hiding in the basement, and a final strike killed a civilian at a roundabout in the center of town (see section on al-Bab below).
The lack of capacity of the Syrian Air Force to conduct precise air strikes against military objectives in populated urban areas was apparent in Human Rights Watch’s interviews with four Syrian Air Force defectors. They said they did not have the capacity to identify and target specific military objectives, and that they believed their commanders, aware of the indiscriminate nature of the strikes, used them in part to instill fear among the civilian population in opposition-strongholds and to deprive the opposition of local support.
For example, a brigadier general who said that he served in the Ministry of Defense at a military airport near Damascus until he defected in August 2012 told Human Rights Watch that pilots did not have accurate spotting technology, but that from the Syrian government’s perspective, inaccurate strikes served their purpose. Discussing strikes in Aleppo, he said:
It is difficult [for the pilots] to know where they are hitting. Their strike range is maybe 300 to 400 meters from a target. From their perspective it is okay because they find a spot where the FSA is and hit it, give or take a few hundred meters. They [the commanders] want people to be afraid. They want people to move out of Aleppo.
A second brigadier general, who said that he served for 40 years in the air force defense section of the Ministry of Defense before defecting, told Human Rights Watch that “the point of the strikes is to get people to hate the FSA.”
A pilot, a colonel in the Syrian Air Force, who defected in September 2012, told Human Rights Watch:
Ninety percent, even 95 percent of the bombing is random. What’s the purpose? To scare the population, terrorize people, and make them turn their back on the revolution.… Pilots would dive in, attack, but then go back up without shooting. Then they [the commanders] would force them, ordering them to “shoot!”
 For a detailed discussion on applicability of IHL to the conflict in Syria, see Human Rights Watch, “They Burned My Heart”; The International Committee of Red Cross (ICRC) concluded in July 2012 that the situation in Syria amounts to a non-international armed conflict. See: ICRC, “Syria: ICRC and Syrian Arab Red Crescent maintain aid effort amid increased fighting,” July 17, 2012, http://www.icrc.org/eng/resources/documents/update/2012/syria-update-2012-07-17.htm (accessed February 2, 2013). International human rights law, including the International Covenant on Civil and Political Rights (ICCPR), also continues to be applicable during armed conflicts. These treaties guarantee all individuals their fundamental rights, many of which correspond to the protections afforded under international humanitarian law including the prohibition on torture, inhuman and degrading treatment, non-discrimination, and the right to a fair trial for those charged with criminal offenses. It also includes the basic freedom from arbitrary detention.
 Geneva Convention for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field, adopted August 12, 1949, 75 U.N.T.S. 31, entered into force October 21, 1950; Geneva Convention for the Amelioration of the Condition of Wounded, Sick and Shipwrecked Members of Armed Forces at Sea, adopted August 12, 1949, 75 U.N.T.S. 85, entered into force October 21, 1950; Geneva Convention relative to the Treatment of Prisoners of War, adopted August 12, 1949, 75 U.N.T.S. 135, entered into force October 21, 1950; Geneva Convention relative to the Protection of Civilian Persons in Time of War, adopted August 12, 1949, 75 U.N.T.S. 287, entered into force October 21, 1950; Convention (IV) Respecting the Laws and Customs of War on Land and the Annexed Regulations Concerning the Laws and Customs of War on Land of 18 October 1907 (Hague Regulations), 3 Martens Nouveau Recueil (ser. 3) 461, 187 Consol. T.S. 227, entered into force January 26, 1910. While Syria is not a party to the Second Additional Protocol that applies to non-international armed conflict, some of the Protocol’s provisions are widely recognized as part of international customary law.
See ICRC, Customary International Humanitarian Law, rule 9, citing Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I), adopted June 8, 1977, 1125 U.N.T.S. 609, entered into force December 7, 1978, art. 52(1),http://www.icrc.org/customary-ihl/eng/docs/v1 (accessed December 10, 2012).
 See ICRC, Customary International Humanitarian Law, rule 8, citing Protocol I, art. 52(2).
 Ibid, rule 8, citing military manuals and official statements.
 Ibid, rule 12, citing Protocol I, art. 51(4)(a).
 Ibid, rule 14, citing Protocol I, arts. 51(5)(b) and 57.
 See ICRC, Commentary on the Additional Protocols (Geneva: Martinus Nijhoff Publishers, 1987), p. 684.
 See ICRC, Customary International Humanitarian Law, rule 15, citing Protocol I, art. 57(1).
 See ICRC, Customary International Humanitarian Law, rule 15, citing Protocol I, arts. 57(1-2).
 See ICRC, Customary International Humanitarian Law, rule 16, citing Protocol I, art. 57(2)(a).
 See ICRC, Commentary on the Additional Protocols, pp. 681-82.
 See ICRC, Customary International Humanitarian Law, rule 17, citing Protocol I, art. 57(2)(a)(ii).
 Ibid, rules 22-24.
 Ibid, rule 97.
 Ibid, rule 140.
 Ibid, rule 2, citing Protocol I, art. 51(2).
 Additional Protocol I, art 51 (2).
 See ICRC, Customary International Humanitarian Law, p. 574, citing for example International Criminal Tribunal for the former Yugoslavia, Delalic case, Case no. IT-96-21-T, Judgment, Trial Chamber II, November 16, 1998.
 See ICRC, Customary International Humanitarian Law, p. 554.
 See ICRC, Customary International Humanitarian Law, rule 156.
 According to the Appeals Chamber in Blaskic: “In light of the customary rules on the issue [Protocol I, arts. 51(2-4), Protocol II, art. 13(2), and the Hague Regulations of 1907, art. 25], the Appeals Chamber holds that attacks in which civilians are targeted, as well as indiscriminate attacks on cities, towns, and villages, may constitute persecutions as a crime against humanity.” International Criminal Tribunal for the former Yugoslavia, Blaskic (Appeals Chamber), July 29, 2004, para. 159.
 ICRC, Customary International Humanitarian Law, rule 156.
 ICRC, Customary International Humanitarian Law, rule 156.
 ICRC, Customary International Humanitarian Law, rule 153.
 International Institute for Strategic Studies, The Military Balance 2011 (London: Routledge, 2011), p. 331.
Colin King, ed., Jane’s Explosive Ordnance Disposal 2007−2008, January 15, 2008, (Surrey, UK: Jane’s Information Group Limited, 2008), CD-edition.
 International Committee of the Red Cross (ICRC), “Weapons that may Cause Unnecessary Suffering or have Indiscriminate Effects,” (Geneva: ICRC, 1973), http://www.loc.gov/rr/frd/Military_Law/pdf/RC-Weapons.pdf.
 Human Rights Watch documented the use of such weapons in populated areas in three attacks examined in this report. Witnesses in Latakia in particular reported that helicopters frequently dropped such improvised bombs. Witnesses were able to determine that a helicopter dropped an improvised bomb because they could either see the barrel (which looks different from a standard bomb) while it was falling or founds remnants of the barrel after the attack. Shrapnel from standard, factory-produced high-explosive bombs are often thick pieces of steel, while an improvised bomb usually leave remnants from the barrel, drum or pipe used as the container and the fragmentation media.
 By reviewing satellite imagery, Human Rights Watch established that the helicopter was flying over the town of Dabaa just north of al-Quseir in the Homs governorate. [Throwing barrels of TNT amid the laughter of al-Nasiriya gang], video clip, YouTube [N.D.], http://youtu.be/8IYbsnAfcRQ (accessed January 30, 2013). A second video shows similar improvised munitions in a helicopter hovering over Tel Zubaydah ten kilometer south-east of Homs, but no drop.” Leaked: Syria throwing TNT bombs from helicopter,” video clip, YouTube [N.D.], http://youtu.be/gtoOH9FMZvk (accessed January30, 2013).
 For a good overview of weapons used by the Syrian Air Force, see: Brown Moses, “The Weapons of the Syrian Air Force,” Brown Moses (blog), December 31, 2012, http://brown-moses.blogspot.fr/2012/09/the-weapons-of-syrian-air-force.html (accessed February 1, 2013).
 Hewson, ed., Jane’s Air-Launched Weapons, Issue 44 (Surrey, UK: Jane’s Information Group Limited, 2004), page 418.
 “FNN Syria Vacuum bombs being used to shell civilians,” video clip, YouTube, October 29, 2012, http://www.youtube.com/watch?v=JHYbVmGgvAQ (accessed January 13, 2013); “Douma - A New Air raid with Vacuum Bombs,” video clip, YouTube, January 3, 2013, http://www.youtube.com/watch?v=mnuqhM-9xtI (accessed January 31, 2013).
 “Brown Moses: OFAB sightings in Syria,” video playlist, YouTube, [N.D.] http://www.youtube.com/playlist?list=PLPC0Udeof3T4kAEbZ97urYh2aoQy9VdyQ (accessed February 1, 2013). See also: Brown Moses, “Collected ODAB Thermobaric Bomb Evidence,” Brown Moses blog, September 17, 2012, http://brown-moses.blogspot.fr/2012/09/collected-odab-thermobaric-bomb-evidence.html (accessed January 31, 2013).
 See: ICRC, “Weapons that may Cause Unnecessary Suffering or have Indiscriminate Effects.”
 Human Rights Watch interviews, al-Bab, December 12, 2012.
 Human Rights Watch interview with a former brigadier general in the Syrian Air Force, Turkey, October 9, 2012.
 Human Rights Watch interview, Turkey, October 2, 2012.
 Human Rights Watch interview with former Syrian Air Force colonel, Jordan, November 4, 2012.