Written by Astha Priya
“Terrorism targets the very foundations of our societies and directly challenges our shared values of peace, justice, and human dignity
~United Nations
Recently, Pakistan has entered the Security Council as a non-permanent member for next two years, starting from 1st January 2025. Ambassador Akram, Pakistan’s top Diplomat at United Nations (UN), remarked that “Pakistan will play an active and constructive role, in accordance with the UN Charter, to halt wars, promote the pacific settlement of disputes and contain the negative impacts of great power rivalries, the arms race, new weapons and domains of conflict as well as the spreading scourge of terrorism”.
The modern international world has witnessed the emergence of non-state actors, which although do not exercise formal territorial control but do influence international politics. One of the challenges associated with the emergence of non-state actors is ‘terrorism’, which is a menace to humanity. One of the most debatable issues regarding terrorism is that ‘whether the State which is a victim of terrorist attack has the right to use force against the attackers? The paper analyses the legality of such ‘use of force’ based on two articles of United Nations Charter- Article 2(4), which prohibits the use of force by the States and Article 51, which provides for self-defence as an exception to this general prohibition. It also examines the scope of these two Articles, focussing on their interpretation in context of terrorist acts by non-state actors. It further delves into the relevance of ‘effective control’ test propounded by International Court of Justice in Nicaragua case[1] and the interpretation of the term ‘armed conflict’ under these Articles. References has been taken from various Conventions, Resolutions of United Nations Security Council and landmark cases decided by International Courts to examine the legality of use of force against non-state actors (especially, terrorist organisations) involved in terrorist actions.
Traditionally, states were considered as the only primary actors under international law. However, emergence of various factors created a conducive environment for the rise in the activities of non-state actors (NSAs). Some of those factors include increase in the multipolarity of the global order, globalization, democratization as well as evolution of information and communication technology (ICT). These factors, together led to the growth of non-state actors (hereinafter referred to as NSAs). With the passage of time, these NSAs grew in number and gradually evolved as one of the important players in the international arena. Actors which can be classified as NSAs not only include Non-Governmental organisations (NGOs), lobby groups, media and multinational companies, but also organised crime syndicates as well as terrorist organisations.[2] However, the emergence of NSAs has presented myriad challenges to the international world. On one hand, NSAs such as International non-governmental organisations and multinational companies have worked for boosting cooperation and peace among the Nations; on the other hand, NSAs such as terrorist organisations have posed a threat to the peace and security of the Nations. Andrew Clapham has brought into light the threats which are posed by NSAs to humanity. He opines that NSAs must comply with the principles of International Human Rights law and put forth arguments in that behalf.[3]
The term ‘non-state actor’ has not been defined under international law. However, its meaning can be understood by comparing it with the characteristics of ‘State actor’. ‘State’ has a definite territory, a permanent population, a government and capacity to enter into international relations[4]. The ‘non-state actor’ does not fit into the criteria of State as it does not exercise formal control over a defined territory and have no permanent population, but does influence the decisions in the international relations.
‘Terrorism’ is one of the various challenges posed by the rise of NSAs, which may lead to annihilation of the international world. However, there is no universal definition of the term ‘terrorism’. The interpretation of the term ‘terrorism’ has been left on the wits of the States themselves. What may be terrorism for one State may not be terrorism for another State. Due to the persisting differences in the opinion of States, no consensus as to the universal definition of the term ‘terrorism’ has been reached. However, various attempts have been made by United Nations (UN) to define ‘terrorism.’ In 1994, United Nations General Assembly (UNGA) reiterated that the terrorist attacks are ‘criminal and unjustifiable wherever and by whoever committed…..’. Further, the General Assembly, in its resolution 49/60[5] declared that “Criminal acts intended or calculated to provoke a state of terror in the general public, a group of persons or particular persons for political purposes are in any circumstance unjustifiable, whatever the considerations of a political, philosophical, ideological, racial, ethnic, religious or any other nature that may be invoked to justify them”. United Nations Security Council (UNSC) also attempts to define ‘terrorism’, in Para 3 of its Resolution 1566 (2004)[6] in the following terms:
“…….criminal acts, including against civilians, committed with the intent to cause death or serious bodily injury, or taking of hostages, with the purpose to provoke a state of terror in the general public or in a group of persons or particular persons, intimidate a population or compel a government or an international organization to do or to abstain from doing any act”
Therefore, it can be concluded that the term ‘terrorism’ refers to those actions which are intended to instil a sense of terror in the general public or compel the government or international organisation to do or abstain from doing an act. ‘Terrorism’ can take various forms. It may or may not involve ‘armed attacks’. For instance, cyber terrorism is one such form of terrorism where there is no involvement of arms.
The September 11 attacks by Al-Qaeda terrorists was an appalling event which compelled the Nations to re-evaluate their national and foreign policies in order to prevent recurrence of such incidents in later times. This incident centre staged the problem of terrorism and triggered the deliberations relating to counter terrorism on various international forums, especially United Nations Security Council (UNSC). On 11th September 2001, four commercial airliners were hijacked by nineteen Al-Qaeda terrorists (out of which 15 were from Saudi Arabia, 2 from United Arab Emirates, 1 from Lebanon and 1 from Egypt). They crashed two of the airliners into the World Centre Towers, at New York City, the third one into the Pentagon (Virginia) which was the Headquarters of the United States Department of defence, and the fourth one crashed in Pennsylvania when the passengers were trying to take over the plane and started revolting against the hijackers to protect themselves. More than 3000 people belonging to more than 80 different Nations died in the incident.[7] President George W. Bush, then President of the United States (US) condemned the attack in the following words:
“The attack took place on American soil, but it was an attack on the heart and soul of the civilized world. And the world has come together to fight a new and different war, the first, and we hope the only one, of the 21st century. A war against all those who seek to export terror and a war against those governments that support and shelter them”[8].
This attack led the United States under the Bush administration to relook into the threat as well as the responses to the threat. The Bush administration responded to the incident vigorously and the ‘war on terrorism’ began. The responses involved: diplomatic responses, attacking on the financial channel of the terrorists, military responses where operation ‘Enduring Freedom’ was started which gathered support of many countries (from United Kingdom to Australia to Japan), Foreign Terrorist Tracking Task Force was established to prevent terrorist entering in United States, new stringent anti-terrorist laws were being enforced, humanitarian aid was being provided to Afghanistan, homeland security measures were being adopted including increase in safety of airlines to prevent any further terrorist attacks in America, measures were being taken to prevent American-Muslim hate crimes and maintaining cooperation between the two communities.[9]
The approach of the United States towards terrorism underwent various changes with the passage of time and led to evolution of three strategies to combat terrorism. First strategy was the strategy of ‘counter terrorism’, which emphasised on the terrorists themselves and involved traditional counter terrorism measures. It was the initial strategy adopted by the Bush administration as the response to the threat of terrorism. Three questions were asked and answered by the Administration itself in order to conceptualise the act of the terrorism and to find out the strategy which could be adopted by the administration in response. The first question asked was “who attacked our country?” The terrorists and governments supporting them were identified as ‘attackers’. The second question asked was “why do they hate us?” (that is, why did they commit these attacks?) The answer that the administration gave to the question was that they (terrorists) hate freedom and aim to destroy providers of such freedom. The third question which was asked was “how will we fight and win this war?” The administration decided to employ every means (diplomatic, financial, law enforcement, as well as necessary weapons of war) to eradicate Al-Qaeda and its supporters and followed ‘with us or against us policy’. Those States that did not come to support the US in the war against terrorism were regarded as ‘hostile States’. This strategy led to the war in Afghanistan. The policy, no doubt, was successful to the extent that it weakened the financial network of Al Qaeda, and destroyed many of its terrorist camps. However, the United States failed to get its hands on Al Qaeda leader Osama Bin Laden.[10]
By recognising failures faced by the US in combating terrorism by adopting the strategy of counter terrorism, it started modifying its policies and broadened the scope of answers to the above discussed three questions. The definition of ‘enemy’ was expanded by including, in addition to terrorists and their supporters, those possessing Weapons of Mass destruction as well as their rogue regimes. The year 2002 witnessed the evolution of the strategy of ‘pre-emption and pre-eminence’. This strategy called for modification in the conceptualization of the threat of terrorism and how to tackle the problem. The focus of the United States was then shifted to those nations which were involved in proliferation of weapons of mass destruction such as Iran, Iraq and North Korea. The strategy of pre-emption, as per the International law, could only be adopted where there is an ‘imminent threat’ to a Nation. However, the United States were reluctant to follow this rule and Iraq was at the target. On the basis of its seven propositions[11] That indicated certain connections of Iraq to Al Qaeda and possession of ‘weapons of mass destruction’ by Iraq under Saddam Hussain’s Government in defiance to United Nations Resolutions, US got casus belli to dethrone Saddam Hussain’s Government in Iraq. However, the case was different in North Korea, which was also in possession of nuclear weapons in defiance of UN Resolutions. However, the US did not pay much attention to North Korea and Iran in that respect.
Again, recognising the flaws in the second strategy, the United States found that military policies were not enough to resolve the issue of terrorism. It led to the evolution of the third policy ‘forward strategy of democratization of the Middle East’, which aims at identifying the root causes of the problem and providing a long-term solution of the problem.[12] Again the above discussed three questions were revisited by the administration and a different set of answers were provided. The United States started promoting democratic and representative government in Middle East countries, especially countries such as Iran, Iraq, Israel, Saudi Arabia and Syria for the purpose of addressing the root cause of the issue of terrorism.[13]
Therefore, it can be noted here that the approach of the United States towards terrorism evolved after the September 11 attacks. Initially, its responses were broadly based on military actions and use of force, but ultimately, it conflated the initial policies with non-military policy of promoting democratization of the Middle East. David Hastings Dunn in his paper ‘Bush, 11 September and the Conflicting Strategies of the ‘War on Terrorism’’, concluded that the Bush administration’s approach towards ‘war on terrorism’ has been dynamic rather than static thus outlining the strategies which evolved as a consequence.
The Security Council’s first landmark resolution pertaining to terrorism was Resolution 635[14], which was an aftermath of Lockerbie tragedy (Pan Am Flight 103)[15], one of the horrendous terrorist attacks in the history of the United Kingdom where 270 people were killed. The Resolution asserted that terrorism is a threat to international peace and security.
Resolution 1368 was passed by Security Council to condemn the attacks of September 11 in strongest terms[16]. This resolution also reaffirms the Right of self-defence under Article 51 of the UN Charter. The Resolution states that:
“The Security Council, Reaffirming the principles and purposes of the Charter of the United Nations, Determined to combat by all means threats to international peace and security caused by terrorist acts, Recognizing the inherent right of individual or collective self-defence in accordance with the Charter,… Unequivocally condemns in the strongest terms the horrifying terrorist attacks which took place on 11 September 2001 in New York, Washington (D.C.) and Pennsylvania and regards such acts, like any act of international terrorism, as a threat to international peace and security”[17]
Another Resolution adopted unanimously by the Security Council in the wake of September 11 attacks was Resolution 1373[18], which imposed certain binding commitments on the member States. The Resolution called upon the States to curb terrorist funding or any kind of active or passive support to terrorists. Necessary steps were to be taken by the States to prevent commission of terrorist acts. It mandated the States to become parties to various conventions and protocols relating to terrorism. The States were further required to implement Security Council Resolutions 1269[19] and 1368[20]. One of the most important developments introduced by this Resolution was the monitoring mechanism. A counter terrorism Committee (CTC) was established under the Resolution to look after the implementation of the commitments by the States.
These two Resolutions are part and parcel of the discussion when it comes to terrorism. These Resolutions indicate a hardened approach of the Security Council towards ‘terrorism’ after the September 11 attacks. It has been noted that there has been a rise in the number of terrorism related Resolutions adopted by the Security Council after September 11 attacks.[21] This shows that the Security Council acknowledged the seriousness of the threat posed by terrorism to international peace and security after witnessing the horrific incident of September 11.
“It always lies within the power of a State, to gain political or other advantages over another not only by employment of force, but also by direct recourse of war”.[22] Therefore, initially, at least before the twentieth century, use of force was not prohibited under the international law and was a lawful means for the States to fulfil their own interests. During the earlier times, doctrine of Just war was prevalent, where the war was considered as just if it is in response to the loss or damage caused by another nation. This doctrine was challenged during the 16th century, and with the advent of modern Nation States, it became obsolete. This theory was then replaced by the positivist approach, the foundation of which lies in the sovereignty of States. Positivist approach rejects the non-consensual limitations on the discretion to choose the means of international intercourse including the war. However, it did acknowledge that, before resorting to the use of force, the State must exhaust all the peaceful means.
However, during the twentieth century, the legal system pertaining to the use of force changed and the rules became more stringent. Hague Conventions for Pacific Settlement of International Disputes, 1899 and 1907 provided that if a conflict arises, before resorting to the arms, the signatory States must have recourse to good offices or mediation.[23] Then, as a consequence of the First World War, Convention on the League of Nations, 1919 obligated the Parties to resort to the judicial settlement, arbitration, or enquiry, before resorting to war.[24] It made recourse to arms as a last resort. 1928 Kellogg–Briand Pact[25] also criticized the resort to war for solving international controversies. The Pact was nothing but an effort to prevent another world war, in which it clearly failed. Ultimately, as a result of the Second World War, the United Nations Charter, 1945 was formulated.
The UN Charter is the constitutional document of the United Nations, which plays a vital role in the maintenance of peace and security among the Nations. It spells out various rules and regulations that seek to maintain international peace and security. The Preamble of charter brings out the aim and object of the Charter, one of them being ‘to save future generations from the scourge of war’. Article 1 of the UN Charter further brings out the purposes of the United Nations. One of the primary purposes of the United Nations is to maintain international peace and security. Article 2(4) has been incorporated to fulfil this purpose of the United Nations. The principle which has been incorporated under Article 2(4) is universal in nature as it prohibits the use of force by the States in the following terms:
“All members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any State, or in any other manner inconsistent with the purposes of United Nations”
The word ‘shall’ have been used in the provision which is an indicator that the provision is mandatory in nature and is binding on member States of the UN Charter. The principle imbibed in this provision is also a customary international law and a peremptory norm (A norm accepted and recognised by the international community of States as a whole as a norm from which no derogation is permitted and which can be modified only by a subsequent norm of general international law having the same character)[26]. Hence, non-member states are also bound by this principle, but their obligation arises from Customary International law and not Article 2(4) of the UN Charter.
The Article can be read in two parts: first part is refraining the use of force against the territorial integrity or political independence of any State. It tends to maintain sovereign equality of the States, and to protect the right of self-determination of the people of States. Second part is refraining use of force in any other manner inconsistent with the purposes of the UN Charter.[27]
In the discussion related to the scope of Article 2(4), the question that arises is: whether the Article limits the scope of the prohibition only to the States or does it extend to the use of force by the NSAs such as terrorist organisations? The text of a treaty must be interpreted as it is, unless it leads to an obscure outcome. Therefore, giving the objective interpretation to Article 2(4), it is very clear that the general prohibition is applicable only to the use of force by the States. However, the ‘use of force’ by NSAs may be included within the scope of Article 2(4) when the act is attributable to a State. When a State provides that level of support to NSAs in order to make the act attributable to that State, the State responsibility arises under International Law Commission’s (ILC) Draft Articles on State Responsibility (DASR). It is further pertinent to highlight what level of support by the States leads to ‘attribution’. On this point, the International Court of Justice (hereinafter referred to as ICJ), in the Nicaragua case[28], held that the responsibility of the State will arise where the State had ‘effective control’ over the military or paramilitary actions. Therefore, the standard for attribution as set by ICJ is ‘effective control.’
Another debate encompasses the term ‘international relations.’ Whether for the application of prohibition under Article 2(4), use of force must cause damage to another State? Whether damage to terra nullius also included? The term used in the provision is ‘international relations.’ The provision does not expressly provide that the damage must be caused to States, but the use of force must affect the relations between the States.[29]
The term ‘use of force’ has also been subjected to a long debate as to what kind of actions are included in ‘use of force’. Factors such as effect, hostile intent and gravity of action are taken into consideration while deciding whether an action amounts to the ‘use of force’. However, there are some ‘subsequent agreements’[30] which may be referred for the purpose of interpretation of Article 2(4) of the UN Charter and the term ‘use of force’ mentioned therein. Subsequent agreements are one of the authentic means of interpretation according to Article 31 (3) of the Vienna Convention on the law of the Treaties 1969 (VCLT). Some of the subsequent agreements which may aid in interpretation of Article 2(4) of the UN Charter are: 1970 United Nations General Assembly Resolution 2625 (XXV)[31], United Nations General Assembly’s 1974 definition of ‘aggression’[32], General Assembly Resolution 42/22 (1987) and World Summit Outcome Document, 2005[33].
Principle 1, Para 9 of Friendly Relations Declaration, 1970 states that ‘Every State has the duty to refrain from organizing, instigating, assisting or participating……in… terrorist acts in another State or acquiescing in organized activities within its territory directed towards the commission of such acts, when the acts referred to in the present paragraph involve a threat or use of force’[34]. It means that a State shall not involve itself in terrorist activities in another States and also not to support or acquiesce to such activities in its territory where such act involves threat or use of force. Para 6 of General Assembly Resolution 42/22[35] also contain similar prohibition in following terms: ‘States shall fulfil their obligations under international law to refrain from organizing, instigating, or assisting or participating in paramilitary, terrorist or subversive acts, including acts of mercenaries, in other States, or acquiescing in organized activities within their territory directed towards the commission of such acts’. Therefore, it can be noted here that some of these agreements also refers ‘acts of terrorism’ as a use of force and appeals for its prohibition. Now again the question arises whether a state can use force against such terrorist organisations which are involved in ‘use of force’? The answer to this question lies in Article 51 of the UN Charter.
The prohibition on use of force under Article 2(4) of the UN Charter is not absolute. Two exceptions have been carved out under the Charter itself where the force may be exercised. First exception lies in the vesting of power to use force in the Security Council under Article 42 (Chapter VII) of the UN Charter. Under the said Article, the Security Council can call for measures involving action by air, sea or land forces when non-armed measures are considered or proved to be inadequate by the Council in maintaining peace and security.[36] Another exception has been recognised under Article 51 (Chapter VII) of the UN Charter, which provides for the unilateral use of force by the State in case of occurrence of an ‘armed attack’, in the following words:
“Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.”[37]
This Article is a part of the collective security system provided under Chapter VII of the UN Charter and is also a part of customary international law.[38]. This article permits the use of force for the purpose of defending oneself. It permits both individual and collective self-defence. It means that the state may act in self-defence individually or call upon the other States for their support in taking such a measure under Article 51. There has been a long debate encompassing this particular right of the States under the UN Charter. As we live in an era where terrorism has emerged as one of the biggest global issues, the number of States claiming right of self-defence under Article 51 has surged. It has been argued that one of the reasons behind strengthening the claims under Article 51 is the inability of the Security Council to respond strongly against the terrorism. Between 1945 and late 1980s, the Security Council failed to use its authority[39] and did not recognize any terrorist act as a threat to or breach of the peace in the sense of Article 39[40] of the UN Charter and therefore, no enforcement actions were taken against the terrorist organisations. Disappointed by this attitude of the Security Council, States had to take recourse to Article 51 for defending themselves. However, the Article also provides that the State taking any measure of self-defence under this Article, shall inform about such measures to the Security Council. This is a safeguard which has been incorporated under Article 51. It means that a state can use force in self-defence if there is an occurrence of ‘armed attack’ provided that the State using the force must also fulfil the requirement of ‘necessity’ and ‘proportionality’.
The Article provides that the States may resort to unilateral use of force if there is an ‘armed attack’ against the State. It must be noted here that Article 51 is responsive in nature and the question of self-defence arises when the ‘armed attack’ has actually taken place. However, the Charter does not define the term ‘armed attack’. There was no comprehensive debate or discussion on the term ‘armed attack’ in the UN Founding conference held in San Francisco in 1945 and was left open to interpretation. The interpretation of this term has led to widening of the scope of Article 51.
Whether attacks by private terrorist organisations are included under the term ‘armed attack’? The answer to the question is still unsettled. Traditionally, the term ‘armed attack’ was applied only to ‘States’. It must also be noted here that the Article talks about ‘armed attack’ and says nothing about the attacker. Here exists a gap in Article 51. When Article 51 is read in conjunction with article 2(4) of the UN Charter, few opinions mention that the makers intentionally left a gap between them and despite the fact that Article 51 grants an exception to Article 2(4), it is of a different nature and includes NSAs in its interpretation.[41] If textual interpretation of Article 51 is taken into consideration, and read in isolation to Article 2(4), the Article nowhere clarifies that the action of use of force in self-defence can only be taken against States. But, if we read it with Article 2(4), the words used under Article 2(4) are ‘against the territorial integrity or political independence of any State’, whichindicates that Article 51 although does not use the word ‘state’, is available only against States.
However, after the September 11 attacks, the debate as to whether terrorist attacks are included under the term ‘armed attack’ again gained momentum. It was argued by many that September 11 attacks can be categorised as an ‘armed attack’ and the military action of United States was therefore justified. This view was supported by North Atlantic Treaty Organisation (NATO), Organisation of American States (OAS), and countries like Russia and China.What was the role of September 11 attacks in this respect was that it brought into light the state practice that the terrorist attacks by private actors fall within the ambit of Article 51 and States can take military actions against such NSAs.
Initially, the restrictive interpretation of Article 51 was in vogue. An attack by NSAs could be counted as an ‘armed attack’ if it could be imputed to a particular State. In case of Nicaragua[42], the ICJ laid down the test of ‘effective control’ to determine whether an act is attributable to the State or not. If a state has effective control over the actions of terrorist organisations, then only the defensive military action could be justified. The Court also shed light on the relationship between ‘aggression’ and ‘armed attack’. The Definition of Aggression was used as a benchmark to decide whether an attack is an ‘armed attack’. The Court further held that ‘armed attack’ includes attack by regular forces across international borders, or sending by or on behalf of the State of armed bands, groups, irregulars or mercenaries in the sense of Article 3(g) of Definition of aggression, including substantial involvement therein. However, the Court gave a very narrow and ambiguous interpretation to the term ‘substantial involvement’, by merely specifying that it does not include ‘assistance provided to the rebels in the form of provision of weapons or logistical or other support’. The Court also rejected inclusion of ‘passive support to attacks by private actors’ and ‘incapability to prevent attacks’ in term ‘substantial involvement’. However, the State practice indicates that the scope of the term ‘substantial involvement’ has broadened. For instance, the United States has justified its military action on the ground that a State has shown tolerant behaviour towards the terrorist groups on its territory. The Security Council has not condemned such measures and the international community has also not dissented to such actions. Even in the 2002 National Security Strategy, the United States unequivocally declared that it would no longer distinguish between terrorists and ‘those who knowingly harbour or provide aid to them.
It was clarified by the Court that the Right of Self-defence is not limited to the conditions provided under Article 8 (Conduct directed or controlled by a State) and 11 (Conduct acknowledged and adopted by a State as its own) of DASR. However, this view of the ICJ was criticized as being overly restrictive in nature. Judge Schwebel argued that ‘financial and logistical support’ should be included within the ambit of ‘substantial involvement’. Judge Jennings criticized this interpretation by stating that exclusion of ‘logistical and financial support’ poses a difficulty to understand what exactly the term ‘substantial involvement’ includes.[43] Also, in Israeli Wall opinion[44]the ICJ holds on its traditional view by observing that “Article 51 of the Charter…recognizes the existence of an inherent right of self-defence in the case of armed attack by one State against another State”. ICJ rejected Israel’s claim of right of self-defence under Article 51.[45] Again the requirement of ‘attribution’ was reiterated in Armed activities on the territories of Congo[46]. In that case, Uganda was carrying on certain armed activities in Democratic Republic of the Congo (for brevity, DRC) under the claim of self-defence. But the Court dismissed the claim of Uganda for the reason that none of the essentials triggering the right of self-defence existed there and also, that no sufficient evidence was produced to prove the fact that DRC had provided any kind of military or political aid to rebel groups acting against Uganda in its territory, or that DRC has breached its duty of vigilance by neglecting the activities of such rebel group acting against Uganda in its territory.[47] Therefore, from these majority decisions of ICJ, it is clear that it supported the restricted view of ‘armed attack’ by reiterating the necessity of ‘attribution’ for invoking Article 51 of the UN Charter. However, the decision in Israeli walls opinion[48] was criticized by some of the Judges who were of the opinion that Self-defence was available even if the act cannot be attributed to a State.
However, the current State practice indicates the dilution of Nicaragua’s ‘effective control’ test. After the September 11 attacks, the act was not exactly attributed to Afghanistan or Taliban, but still the international community was in favour of the military actions taken by the United States against Afghanistan. It means that the current international community has departed from the restrictive test of ‘attribution’ and is willing to support a more flexible approach. For instance, after the September 11 attacks, NATO proposed a test called ‘directed from abroad’ test. North Atlantic Council, which is the principal decision making body of NATO agreed that if it is ascertained that the attack is directed from abroad, the attack would be covered under Article 5 of the Washington Treaty which provides “the attack against one or more of them in Europe or North America shall be considered as an attack against them all and they all agree that each of them will assist by virtue of Article 51, in taking actions as deemed necessary, including the use of armed force to maintain security of the North Atlantic area.”[49] NATO was of the view that the September 11 attacks were ‘directed from abroad’ and therefore, falls within the ambit of Article 5 of Washington treaty.[50] The State practice shows that the States in order to justify their anti-terrorist measures try to ascertain the link between the terrorist organisations and the host State, rather than applying ‘effective control’ test as held in Nicaragua. The anti-terrorism measures may be taken against states which provide haven to terrorists, or provide support to such activities where such support does not qualify as ‘direction and control’, or have colluded with the acts of such terrorist organisations. Hence, the present scenario suggests that the restricted view taken by ICJ has turned more flexible and lenient.
When the armed attack is attributable to a State, then the victim state may use force against that State, but the controversy arises when the attack is not imputable to any State. In the latter case, whether the Victim State can use force in order to defend its citizens? Many scholars have opined that the attacks by NSA’s are included in the term ‘armed attack’. When the NSA is operating from a State, but the State fails to take any effective measure to prevent attack, the victim/defending state may use force against the NSA. However, the nexus of State is still an important factor to decide whether an attack by a ‘terrorist organisation’ will be considered as an ‘armed attack’ or not. The international law relating to this aspect is still to be settled.
Threshold requirement is another conundrum pertaining to the question of the right of self- defence. Is it required that an attack must attain a particular gravity threshold to trigger the right of self-defence of the defending state? There is no unanimity in the opinion of States as to the ‘threshold requirement’ or ‘gravity of harm requirement’. The authors of Chatham House Principles of International Law on Use of Force in Self-Defence were of the opinion that “an armed attack means any use of armed force, and does not need to cross some threshold of intensity”.[51] However, the ICJ answered this question in affirmative by distinguishing between ‘most grave’ and ‘less graver’ form of use of force in the case of Nicaragua[52] and holding that ‘most graver form of use of force’ can be categorized as ‘armed attack’ and therefore, self-defence can be claimed against such attack. Again, the Court reaffirmed this distinction in the Oil Platform’s case[53]. Further in the case of DRC-Uganda[54]The Court observed that self-defence can only be directed against large scale attacks. Other than ICJ, Eritrea/Ethiopia Boundary Commission in the matter of Jus Ad Bellum Ethiopia’s Claims between The Federal Democratic and The State of Eritrea[55], observed that “localised border encounters between small infantry units, even those involving the loss of life, do not constitute an armed attack for the purposes of the charter.”[56] The Court also differentiated between ‘geographically limited clashes’ and ‘armed attack giving rise to right of self-defence’. The Commission was satisfied that relatively minor incidents were not of a gravity to constitute an armed attack by either State against the other within the meaning of Article 51 of the UN Charter.[57]
However, the State practice points towards the evolving flexibility in the ‘threshold requirement.’ There have been instances where the right of self-defence has been claimed even where the force used was not the gravest form of the use of force as is laid down in Nicaragua. Again, the State Practice indicates departure from Nicaragua. For instance, Israeli operations launched in Lebanon against Hezbollah, who were involved in firings with Israeli soldiers, were held rightful exercise of right of self-defence, even though the Hezbollah attacks did not satisfy the threshold requirement as propounded in Nicaragua.[58]
Another issue connected with the threshold requirement is- whether sporadic attacks, if part of a general policy of violence, can be considered as an armed attack? In Oil Platforms[59] case, the ICJ held that even if taken cumulatively, a series of incidents did not qualify as armed attack on United States. Therefore, it can be said that ‘accumulation doctrine’ has gained recognition when it comes to justification of use of force by self-defence. Even the small acts of terrorism which do not touch the gravity threshold line when considered individually, if crosses the threshold line when taken together and are part of a general policy of violence, will be considered as an ‘armed attack’. Exercise of the right of self-defence will be justified in such cases. However, it has been argued that admission of ‘accumulation doctrine’ is not enough to bridge the existing gap between Article 2(4) and 51 of the Charter, but re-interpretation of ‘threshold’ is required.[60] According to Tom Ruys and Sten Verhoeven[61] ‘substantial involvement’ as held by ICJ in Nicaragua, sets up a higher threshold as it excludes financial and logistical support. It is worth noting here that ICJ has never given a nod to ‘accumulation theory’ in express terms. Initially, the international community was also reluctant to accept the ‘accumulation doctrine’. But considering the present practice, it seems that they are willing to accept the doctrine as a part of international law related to use of force. As Christian Tams puts it, ‘states seem to have shown a new willingness to accept the “accumulation of events” doctrine which previously had received little support’[62]
When it comes to the countermeasures against terrorism, military actions should not be the first resort. At first, recourse must be taken to diplomatic measures. The defending states must appeal to the government of the state where the terrorist acts have been planned to take suppressive measures against such actions. If such a State is reluctant to take such measures, military actions may be taken to curb the threat. However, Carsten Stahn argues that extending the right of self-defence against state harbouring terrorism will amount to over broadening of the right.[63] Military actions are also permissible against terrorist camps or installations from where the terrorist acts were launched. When various terrorist bases are operating from more than one State, the military actions may be taken against such bases established in any of those States, provided the host State failed to suppress the terrorist acts and that particular terrorist group is related to a prior attack and is planning another such terrorist act.
The question which arises here is that, whether a State is justified in taking preventive actions against the targets which are not connected with a previous attack? Taking the current legal position in the view, such pre-emptive actions are not justified under Article 51. However, such actions may be justified under customary international law of self-defence, where using force is justified when there is an ‘imminent threat’ to the defending State from such a target. Underscoring the threat which may be posed by giving place to ‘pre-emptive self-defence’ under Article 51, Carsten Stahn has rightly remarked that ‘once the door of preventive self-defence is open, it can hardly be closed again’[64].
When the State actors themselves are involved with the terrorist actors, military action may be taken against such states also, provided the degree of action shall be proportional to the degree of involvement of the State actors. For instance, military action can be taken to the extent the State actors obstruct the military action by the defending State against the terrorists and not more.
‘Nicaragua is dead, long live Nicaragua’
-by Carsten Cohn[65]
It can be concluded that although Nicaragua continues to be an authority in law related to the use of force, some dilution of Nicaragua rules can be witnessed, especially after the horrendous incident of September 11. The law relating to use of force and right of self-defence is still evolving. Current legal system permits use of force against terrorist organisations, provided that the act is imputable to a state. However, the question of use of force against private terrorist organisations which has no connection with a State is still open to debate. There is still no consensus among states relating to the expansion of the scope of Article 2(4) and 51 of the UN Charter in order to justify use of force against armed attack by private non-state actors. However, viewing the current global situation and concerns related to terrorism, expansion of scope of Article 2(4) and 51 may be the most probable response. There is a possibility that international law may permit the defending States to counter armed attacks by private NSAs, as a part of self-defence.
However, such expansion will come with a price. The loosening of conditions for determining the ‘armed attack’ will provide the States with unbridled license to use force.[66] It may turn article 51 from a defensive tool to a weapon of exploitation. Minimal confrontation may be turned into a full-fledged armed conflict. Also, it must not be forgotten that this is an era of nuclear weapons. Leniency in the conditions triggering the right of self-defence under Article 51 may also lead to weaponization of nuclear weapons in the name of self-defence. The conditions of ‘necessity’ and ‘proportionality’ may also lose relevance in that matter. Therefore, such expansion must also be accompanied by necessary safeguards.
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[1] Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) (Merits) [1986] ICJ Rep 14.
[2]Peter Wijninga, Willem Theo Oosterveld, Jan Hendrik Galdiga, Philipp Marten, ‘State And Non-State Actors: Beyond The Dichotomy’,Joris van Esch, Frank Bekkers, Stephan De Spiegeleire, Tim Sweijs (eds), Strategic Monitor 2014 Four Strategic Challenges,(The Hague Centre for Strategic Studies 2014).
[3]Andrew Clapham, ‘Human rights obligations of non-state actors in conflict situations’ (2006) 88(863) International Review of Red Cross <https://international-review.icrc.org/articles/human-rights-obligations-non-state-actors-conflict-situations> accessed 17 January 2025.
[4] Art 1, Montevideo Convention on the rights and duties of States (adopted 26 December 1933, entered into force 26 December 1934) 165 LNTS 19.
[5] UNGA Res 49/60 (9 December 1994) U.N Doc. A/RES/49/60.
[6] UNSC Res 1566 (8 October 2004) UN Doc S/RES/1566.
[7]White House, The Global war on terrorism: The first 100 days(White House 2001-2009)<https://2001-2009.state.gov/s/ct/rls/wh/6947.htm>, accessed17 January2024.
[8]Ibid.
[9]Ibid.
[10] David Hastings Dunn, ‘Bush, 11 September and the Conflicting Strategies of the ‘War on Terrorism’’ (2005) Vol. 16, Irish Studies in International Affairs 11.
[11] Ibid.
[12] Ibid at 5.
[13] Ibid.
[14]UNSC Res 635 (14 June 1989) UN Doc S/RES/635.
[15]FBI, ‘The bombing of Pan Am Flight 103’ (14 December 2018), <Remembering Pan Am Flight 103 — FBI>, accessed 17 January 2025.
[16]UNGA Res 1368 (12 September 2001) UN Doc S/RES/1368.
[17]UNSC Res 1368 (12 September 2001) UN Doc S/RES/1368.
[18] UNSC Res 1373 (28 September 2001) UN Doc S/RES/1373.
[19] UNSC Res 1269 (19 October 1999) UN Doc S/RES/1269.
[20] UNSC Res 1368 (12 September 2001) UN Doc S/RES/1368.
[21]Hilde Haaland Kramer and Steve A. Yetiv, ‘The UN Security Council’s Response to Terrorism: Before and after September 11, 2001’ (2007) 122 Political Science Quarterly 409.
[22] Charles Cheney Hyde, International Law: Chiefly as Interpreted and Applied by the United States (Little, Brown & Co 1922) 189, cited in W Michael Reisman, ‘Article 2(4): The Use of Force in Contemporary International Law’ (1984) 78 American Society of International Law Proceedings 74 (Cambridge University Press).
[23]Hague Convention (I) for the Pacific Settlement of International Disputes (29 July 1899) 32 Stat. 1779, 1 Bevans 230, art 2; Hague Convention (II) for the Pacific Settlement of International Disputes (18 October 1907) 36 Stat 2199, 1 Bevans 577, Cited in Christine D. Gray, International Law and the use of force (4th edn, OUP 2018).
[24] Covenant of the League of Nations (signed 28 June 1919) (1919) 225 CTS 188 art 2.
[25] General Treaty for the Renunciation of War (Kellogg Briand pact) (signed 27 August 1928) 94 LNTS 57.
[26] International Law Commission, ‘Report of the International Law Commission on the work of its 71st Session’ (29 April – 7 June and 8 July – 9 August 2019) UN Doc A/74/10.
[27] Erin Pobjie, Prohibited Force: The meaning of ‘use of force in international law (Cambridge University Press 2024) <https://doi.org/10.1017/9781009022897.001> accessed 29 January2025.
[28]Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) (Merits) [1986] ICJ Rep 14.
[29] Erin Pobjie, Prohibited Force: The meaning of ‘use of force in international law (Cambridge University Press 2024), <https://doi.org/10.1017/9781009022897.001>, accessed29 January2025.
[30] Vienna Convention on the law of treaties (adopted 23 May 1969, entered into force 27 January 1980) 1155 UNTS 331 art 31.
[31] Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, UNGA Res 2625 (XXV) (24 October 1970).
[32] Definition of Aggression, UNGA 3314 (XXIX) (14 December 1974) (Adopted without a vote on a Report from the Sixth Committee) UN Doc A/RES/29/3314.
[33] United Nations Human Rights Council Resolution 42/22 (8 October 2019) UN Doc A/HRC/RES/42/22.
[34]Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, UNGA Res 2625 (XXV) (24 October 1970).
[35] Human Rights Council Res 42/22 (8 October 2019) UN Doc A/HRC/RES/42/22.
[36] Charter of United Nations (signed on 26 June 1945, entered into force 24 October 1945) art 41.
[37] Charter of United Nations (signed on 26 June 1945, entered into force 24 October 1945) art 51.
[38] Michael Byers, ‘Terrorism, the Use of Force and International Law after 11 September’ (2002) 51(2) International and Comparative Law Quarterly 401, 401–14, citing Ian Brownlie, International Law and the Use of Force by States (Oxford Clarendon Press 1963) 231–80; Bruno Simma (ed), The Charter of the United Nations: A Commentary (Oxford University Press 1994) 661–78; Military and Paramilitary Activities in and against Nicaragua (Nicaragua v USA) [1986] ICJ Rep 14, 102–6, 110, 122–23, paras 193–201.
[39] Christian J Tams, ‘The use of force against terrorists’ (2009)20 EJIL 359.
[40] Ibid.
[41]Divyanshi Goel, ‘The Use of Force vis-à-vis Self-Defence in the United Nations Charter’ (SCC Online, 10 June 2023) <https://www.scconline.com/blog/post/2023/06/10/the-use-of-force-vis-vis-self-defence-in-the-united-nations-charter/> accessed29 January 2025.
[42] Nicaragua(n 26).
[43] Tom Ruys and StenVerhoeven, ‘Attacks by private actors and the Right of Self-Defence’ (2005) 10(3) Journal of Conflict and Security Law 289< https://doi.org/10.1093/jcsl/kri016> accessed 19 January2025.
[44] Legal Consequences of the Construction of Wall in the occupied Palestinian Territory [2004] ICJ Rep 136 < https://www.icj-cij.org/case/131 > accessed29 January2025
[45] ‘International Court of Justice Advisory opinion finds Israel’s construction of wall ‘contrary to international Law’’ <https://press.un.org/en/2004/icj616.doc.htm> accessed 30 January2025.
[46] Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda) (ICJ GL No116) <https://www.icj-cij.org/case/116> , accessed 19 January2025.
[47] Ibid.
[48] Ibid.
[49] North Atlantic Treaty (4 April 1949) art 5.
[50] n 40.
[51] David Kretzmer, ‘The Inherent Right to Self-Defence and Proportionality in Jus Ad Bellum’ (2013)24 (1) The European Journal of International Law 235.
[52] Nicaragua(n 26).
[53] Oil Platforms (Islamic Republic of Iran v United States of America) [2003] ICJ Rep 161 < https://icj-cij.org/case/90 > accessed29 January2025.
[54] Armed Activities on the Territory of the Congo (n 44).
[55] Award on Ethiopia’s Jus ad bellum Claims, 45 ILM (2006) 430.
[56] Reports of International Arbitral Awards, Eritrea-Ethiopia Claims-Partial Award: Jus Ad Bellum- Ethiopia’s Claims, para 11, 465 (2006).
[57] Reports of International Arbitral Awards, Eritrea-Ethiopia Claims-Partial Award: Jus Ad Bellum- Ethiopia’s Claims, para 12, 466 (2006).
[58] Enzo Cannizzaro, ‘Contextualizing proportionality: jus ad bellum and jus in bello in the Lebanese war’ (2006) 88 International review of the Red Cross779.
[59] Oil Platforms (n 51).
[60] Christian J Tams, ‘The Use of Force against Terrorists’ (2009)20(2) European Journal of International Law359.
[61] Tom Ruys and Sten Verhoeven, ‘Attacks by private actors and the Right of Self-Defence’ (2005)10(3) Journal of Conflict and Security Law289< https://doi.org/10.1093/jcsl/kri016> accessed 19 January2025.
[62] Ibid.
[63] Carsten Stahn, ‘Terrorist Acts as “Armed Attack”: The Right to Self- Defense, Article 51 (½) of the UN Charter, and International Terrorism’ (n 40).
[64] Ibid.
[65] Ibid.
[66] Christian J Tams, ‘The use of force against terrorists’ (2009) 20(2) European Journal of International Law 359.
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