In terms of IHL's application to situations of terrorism and counter-terrorism, it is important to understand that the term 'terrorist' in situations of armed conflict has no associated special legal significance and is not defined within IHL. As has been noted previously, acts which are permitted during armed conflict under IHL, such as the targeting of legitimate military targets, do not constitute terrorist acts. Instead, such acts constitute the very nature of armed conflict and, as such, should never be legally defined as 'terrorist', whether under IHL or any other body of international law (including universal instruments against terrorism). To do so would incorrectly suggest that such acts are unlawful and should be criminalized. Instead, persons lawfully engaged in IAC direct hostilities, as defined by IHL, enjoy combatants' immunity from prosecution by the detaining State for lawful acts of war. In contrast, they may be criminally prosecuted for the commission of unlawful acts, such as perfidy which constitutes a war crime. (Especially useful in the drafting of this section was Pejic, 2012, Ch. 7).
Whilst IHL does not recognize 'terrorists' as their own discrete category of actors during situations of armed conflict, it does recognize and prohibit "terrorist" activities. Any acts which would normally be categorized as 'terrorist' as understood within the context of the universal anti-terrorism instruments and criminal justice approaches during peacetime, such as the deliberate perpetration of acts of violence against civilians or civilian objects, constitute war crimes under IHL which should be prosecuted accordingly. For example, the taking of hostages is categorized as an offence under the International Convention against the Taking of Hostages 1979. It is similarly prohibited by Common article 3 of the Geneva Conventions in situations of NIAC, and by article 34 Geneva Convention IV which governs situations where individuals who, during an IAC or occupation, find themselves in the hands of a party to the conflict or occupying power of which they are not nationals. Hostage-taking is further prohibited by the two Additional Protocols (articles 75(2)(c) Additional Protocol I; article 4(2)(c) Additional Protocol II). Significantly too, IHL prohibits indiscriminate and disproportionate attacks which have similar characteristics to terrorist attacks whether perpetrated during peacetime or in situations of armed conflict (see further, e.g., article 51 Additional Protocol I).
Additionally, the two Additional Protocols specifically prohibit acts or threats of violence the primary purpose of which is to spread terror among the civilian population or those no longer taking part in hostilities. Article 51(2) Additional Protocol I and article 13(2) Additional Protocol II specifically prohibit these acts of terrorism in the conduct of hostilities, providing that "[a]cts or threats of violence the primary purpose of which is to spread terror among the civilian population are prohibited". The wording of this provision is important since it is intended to distinguish between acts which have the primary purpose of spreading terror (prohibited under IHL) from acts or threats of violence in the normal conduct of conflict which, whilst likely to cause terror among the civilian population, do not have that as their primary objective and are permissible under IHL so long as all other rules are complied with (see ICRC, 1987, para. 1940).
The International Criminal Tribunal for the former Yugoslavia in the Galic case, in reiterating this criminal mental intent ( mens rea) requirement, stated that such acts fall within the general prohibition of attacks against civilians and that the nature of the acts or threats of violence can vary. It further stated that this prohibition is sourced not only in treaty law, but in customary international law as well, the violation of which constitutes a war crime. "Terrorism" is also expressly not permitted by article 33 Geneva Convention IV which prohibits "all measures of intimidation or of terrorism" as part of collective punishment, which could induce a state of terror, as well as by article 4(2)(d) Additional Protocol II which simply prohibits "at any time and in any place whatsoever ... acts of terrorism".
Many of the international conventions and protocols related to the prevention and suppression of terrorism contain clauses of exception in relation to the military and times of war, stating that activities of armed forces during an armed conflict, governed by IHL, are not governed by the conventions. For example, article 19(2) of the 1997 International Convention for the Suppression of Terrorist Bombings articulates the following:
The activities of armed forces during an armed conflict, as those terms are understood under international humanitarian law, which are governed by that law, are not governed by this Convention, and the activities undertaken by military forces of a State in the exercise of their official duties, inasmuch as they are governed by other rules of international law, are not governed by this Convention.
The application of IHL does not in any way prevent or obstruct a criminal justice response to terrorist acts, including the criminalization of incitement, conspiracy and the financing of terrorist acts. It does not prevent offenders from being held accountable by criminal justice systems. The ICRC has frequently reiterated that compliance with IHL is in no manner an obstacle to the lawful conduct of effective counter-terrorism operations. In fact, full respect for IHL in counter-terrorism activities is a positive contribution to the eradication of terrorism, a key objective of which is to erode the rule of law. Any "grave breaches" of IHL may be criminally prosecuted not only by those States in which the crime occurred or whose citizens were affected, but by any State under the principle of universal jurisdiction; otherwise international jurisdiction applies.
Such complexities and related controversies are likely to continue. The nature of current warfare by well-equipped and organized States against often poorly organized and/or equipped armed groups has resulted in an increasingly asymmetric style of conflict. This is illustrated by the technological and military superiority of the US led coalition against the Taliban and al Qaeda in Afghanistan after its military intervention in 2001 and until its withdrawal in 2016 (but which is likely to see the redeployment of significant numbers of troops, including by the US), and more recently by international efforts to counter ISIL in Syria and Iraq. The unequal balance of military power often results in such opposition groups going underground and adopting styles of warfare contrary to IHL. Examples include locating themselves in the midst of civilian populations, thereby exposing civilians to increased risk and potentially using them as a human shield (prohibited by IHL); and engaging in unlawful, sometimes perfidious, forms of warfare (e.g., wearing civilian clothing when attacking the adversary, conducting indiscriminate attacks, and targeting unlawful civilian targets and protected persons). In addition, incorrect designation of acts that are lawful under IHL as "terrorist" further de-incentivizes non-State armed groups to comply with IHL, with similar consequences. The terrorist label can also impact negatively upon the prospect of securing an amnesty to bring a NIAC to an end (article 6(5) Additional Protocol II).
These and other challenges have put fundamental principles of IHL under strain, such as the concepts of non-reciprocity and the equality of belligerents. IHL is not concerned with the legitimacy of any cause pursued by belligerents (except perhaps self-determination); rather it seeks to ensure that all parties to an armed conflict possess the same rights and obligations in order to ensure equal protection to protected persons and objects impacted by any conflict, which is not provided for within legal frameworks against terrorism. Significantly too, IHL does not confer legitimacy upon non-State armed groups which are a party to a NIAC (see, e.g., article 3 Additional Protocol II which reaffirms the sovereignty of States, including their responsibility to maintain domestic law and order). Where the principle of non-reciprocity is not respected, it reduces the willingness of both State armed forces and non-State armed groups to fully comply with IHL, thereby further endangering the civilian population.
These and other erosions of foundational principles of IHL have been, and continue to be, a cause for great concern for the ICRC as the guardian of IHL. Indeed, some recent forms of counter-terrorism responses and rhetoric have resulted in the blurring of the parameters between armed conflict and terrorism, thereby risking the very tenets upon which IHL is premised. For instance, a common response by some States to violence perpetrated by non-State armed groups is to determine this as 'terrorist' in nature when, in fact, it is provided for under IHL. This is in part explicable by the reluctance of States to afford any form of recognition or legitimacy to non-State armed groups operating on their territory, including through classifying any internal armed struggle as a NIAC.
One further potential impact of States too readily utilizing the 'terrorist' label is that it can have unintended negative consequences, such as the criminalization of otherwise legitimate and appropriate provision of humanitarian assistance. This situation can arise where a non-State armed group, which is a party to a NIAC, is categorized as a terrorist organization. This can result in the group becoming a proscribed terrorist organization at the governmental and intergovernmental levels, including within the United Nations system. Such proscription, in turn, can debar normal humanitarian support which may constitute criminal (unqualified) acts of rendering "material support", "services" and "assistance to", or "association with" terrorist organizations. In response, in its report of 2011, the ICRC highlighted the need for increased understanding by States of the need to better harmonize humanitarian and counter-terrorism policies and legal obligations in order to realize and not undermine their respective objectives (ICRC, 2015). Notably, the ICRC has a treaty-based and statutory mandate, including under the Geneva Conventions, to engage with non-State armed groups, including as part of its key role in encouraging the promotion and respect of IHL by all parties to a conflict.