The use of force against terrorism: a new war for a new century?

The USA demanded that the Taliban regime in Afghanistan close Al Qaida terrorist training camps in Afghanistan, surrender Osama bin Laden and other members of Al Qaida, and open Afghanistan to US inspections. But the Taliban refused.8 The USA with the military assistance of the UK, and pledges of military support from France, Germany, Australia, Canada and others, began Operation Enduring Freedom in Afghanistan on 7 October 2001;9 this operation still continues over six years later. At the start of their military action both the USA and the UK wrote to the Security Council under Article 51, asserting that they were acting in individual and collective self-defence.10 Although NATO had indicated its willingness to act in collective self-defence, the USA preferred not to act through NATO. Nevertheless many member states had forces directly involved in Operation Enduring Freedom at some stage.11 The EU declared its ‘whole-hearted support for the action that is being taken in self-defence in conformity with the UN Charter and the UN SC Resolution 1368’.12

It is not yet clear whether these events have brought about a radical and lasting transformation of the law of self-defence or whether their significance should be narrowly construed in that Operation Enduring Freedom was essentially a one-off, a response to a particular incident based on Security Council affirmation and (almost) universal acceptance by states. Even in the immediate aftermath of 9/11 there was a certain lack of clarity as to the exact scope of the right to use force in self-defence against terrorism and as to whether such a right could be invoked unilaterally. Radically opposing versions of the significance of 9/11 and Operation Enduring Freedom are possible. The temporary agreement between those few states which argued that the legal right to use force against terrorist attacks was already established and those far more numerous states who after 9/11 were apparently for the first time willing to accept it as a new development in the interpretation of Article 51 later dissipated in the disagreement as to whether to use military force against Iraq. Apart from the obvious question of the impact on the law of self-defence, Operation Enduring Freedom’s significance for the controversial doctrines of regime change and intervention should also be considered.


The invocation of self-defence to justify the use of force in response to terrorist attacks had been made by only a few states before 9/11. The USA and Israel had invoked Article 51 to justify the use of force in response to terrorist attacks on nationals abroad, but many regarded their use of force as going far beyond the bounds of this provision. Force was used in response to past terrorist attacks by Israel in 1968 against Beirut and in 1985 against Tunis and by the USA against Libya in 1986, Iraq in 1993 and Sudan and Afghanistan in 1998. In all these episodes force was used against the state allegedly harbouring the terrorist organisation responsible. Israel and the USA used language that combined claims to be acting in response to past attacks and to deter future attacks.13

The first instance was the attack by the Israeli air force on Beirut airport in December 1968; Israel attempted to justify this action as a response to the earlier terrorist attack on an Israeli plane in Athens airport. It said that Lebanon had permitted Arab terrorist organisations to set up their headquarters in Beirut and to maintain training bases in Lebanon, thus officially encouraging warfare by terror against Israel. The Lebanese government had assumed responsibility for the activities of terror organizations. The attack on the Israeli civil aircraft at Athens airport had violated the ceasefire between Israel and Lebanon, and Israel was entitled to exercise its right of self-defence. The Security Council unanimously condemned the Israeli action in Resolution 262 (1968). It is striking that although the USA joined in the condemnation it made a point of explaining that it did so only because Lebanon had not in fact been responsible for the terrorist attack on Athens airport and the Israeli action was not proportionate; it accepted the principle on which the Israeli action was based. A state subject to continuing terrorist attacks could respond by appropriate use of force to defend itself against further attacks; this was an aspect of the inherent right of self-defence recognized in the UN Charter.14

This was not the view of the other states in the Security Council in 1968, but it has been repeated by the USA and Israel in later episodes. Israel in its 1985 attack on Tunis claimed that it was acting against the PLO headquarters in response to terrorist attacks on Israelis abroad by Palestinians. It also claimed that Tunisia had a duty to prevent such attacks being carried out from its territory. Israel said that it was acting in self-defence and the USA in the Security Council debate accepted this argument. But the other member states did not agree and the action was vigorously condemned as an act of armed aggression against Tunisia’s territory in flagrant violation of the UN Charter by 14–0–1 in Resolution 573 (1985). For the other member states the Israeli conception of self-defence was very far from that in international law.15

The USA itself undertook this type of action in 1986 against Libya. In response to terrorist attacks against US citizens abroad for which it said Libya was responsible, US aircraft, flying from bases in the UK with the support of the UK government, attacked targets in Tripoli. The USA reported the action to the Security Council as self-defence under Article 51; its action was a response to past terrorist attacks on nationals and also taken to deter such attacks in the future. Most states rejected this claim saying that self-defence should be narrowly interpreted and could not be pre-emptive. However, the UK and France joined the USA in vetoing the resolution condemning its action.16 The UK accepted that ‘the right of self-defence is not an entirely passive right’; it was within the inherent right of self-defence to try to turn the tide of terrorism and to discourage further attacks.17

The USA used the same wide doctrine of self-defence to justify its action in its response to the alleged assassination attempt on ex-President Bush by Iraqi agents in Kuwait in April 1993. The USA responded in June 1993 by firing missiles at the Iraqi Intelligence Headquarters in Baghdad. It again invoked Article 51 in its letter to the Security Council. The response of the Security Council showed considerable sympathy with the USA and some commentators have tried to argue that this marked the emergence of a new rule of international law allowing such actions in response to terrorism. But in the Security Council it was only Russia and the UK which offered express support for the US legal argument. The UK took a fairly cautious line; it said that force may be used in self-defence against threats to one’s nationals if the target continues to be used in support of terrorist acts against one’s nationals and there is no other way to respond.18 Several states expressed concern, although only China actually condemned the US action. Other states generally said that they understood the US action.19

Similarly, when the USA responded to terrorist attacks on its embassies in Kenya and Tanzania in August 1998 by missile attacks on a terrorist training camp in Afghanistan and a pharmaceutical plant in Sudan, the response of the rest of the world was generally muted. The USA said that the camp had been used by the Al Qaida organization to support terrorism and that the pharmaceutical plant also produced chemical weapons for terrorist activities. It reported its actions to the Security Council under Article 51; it wished to report that the USA had exercised its right of self-defence in responding to a series of armed attacks against US embassies and nationals. It said that it was acting in response to those terrorist attacks and to prevent and deter their continuation. Its attacks were carried out after repeated efforts to convince Sudan and the Taliban regime in Afghanistan to shut down the terrorist facilities. The targets struck and the timing and method of attack used were designed to comply with rules of international law, including the rules of necessity and proportionality.20 Sudan requested a meeting of the Security Council but the issue was not put on the agenda and there was only a very brief meeting with no action taken. There were condemnations of the use of force by the USA by Arab states, the Non-Aligned Movement, Pakistan and Russia. As before, those who refrained from condemnation or expressed support were careful not to adopt the US doctrine of self-defence.21

All these episodes were justified by the states using force as self-defence, but on the basis of the explanations given by Israel and the USA themselves the actions look more like reprisals, because they were punitive rather than defensive. Even if the actions were aimed at those actually responsible for the terrorist attacks, and even if the response could be accepted as proportionate, it is difficult to see how the use of force was necessary, given that the attacks on the nationals had already taken place. The USA and Israel aimed to retaliate and deter and said that their actions were pre-emptive because there was a danger of future terrorist attacks. The problem for the USA and Israel is that all states agree that in principle forcible reprisals are unlawful.22 The General Assembly made this clear in the Declaration on Friendly Relations and the Resolution on the Inadmissibility of Intervention. The Security Council also passed Resolution 188 in 1964, in response to a British attack on Yemen, but declaring in absolute terms that it condemned reprisals as incompatible with the purposes and principles of the UN. This universal agreement that reprisals are not lawful led Israel and the USA to try to stretch the meaning of Article 51, but although other states were not prepared formally to condemn the USA for its attacks on Baghdad, Afghanistan and Sudan, they did not accept the legal argument. Only Russia and the UK were prepared openly to support the legality of the US action in 1993. Russia has since abandoned its brief moment of enthusiasm and returned to a critical approach; even the UK, as so often the main supporter of the USA, took an ambivalent position in 1998. Failure to condemn the USA should be taken to indicate sympathy and understanding rather than acceptance of a legal doctrine which destroys the distinction between reprisals and self-defence and which the USA would never contemplate being used against itself.


Therefore, before 9/11 it was clear that the right to use force in self-defence against terrorist attacks was controversial. But the almost universal support of states for a US right of self-defence in response to 9/11 may be seen as raising the question whether there has been a significant change in the law. For some this is just a continuation of the existing wide right of self-defence; for others it is a new right based on a re-interpretation of Article 51 of the UN Charter, justified by the fiction of instant custom or, more realistically, by universal acceptance by states of a new legal rule; for others the acceptance was merely political and did not serve to create a wider right of self-defence. After 9/11 it seemed that the members of the Security Council were willing to accept the legality of action in self-defence in response to the terrorist attacks on the World Trade Center and the Pentagon as they unanimously passed Resolution 1368 on 12 September and Resolution 1373 on 28 September 2001. These both assert in the preamble that the Security Council is ‘determined to combat by all means threats to international peace and security caused by terrorist acts’ and that it recognizes ‘the inherent right of individual or collective self-defence in accordance with the Charter’.

Although some have expressed doubt as to whether these resolutions actually support self-defence against terrorist actions, because the reference to this is found in the preamble rather than the operative part of the resolutions and the language is that of ‘threat to international peace and security’ rather than ‘armed attack’ under Article 51,23 it seems clear that the members of the Security Council were in fact willing to accept the use of force in self-defence by the USA in response to the terrorist attacks. The reference to self-defence in the preamble is of greater significance than might appear taken in isolation, because the Security Council does not commonly make any express reference to the right of self defence in its resolutions. That is, it seems from the international response to 9/11 that there could, under certain conditions, be a right of self-defence against non-state actors for terrorist attacks. But there are difficulties in establishing the exact scope of this right.

The concept of armed attack after 9/11

One of the most difficult questions arising out of 9/11 is whether the concept of ‘armed attack’ in Article 51 has undergone a revolutionary change so that it now extends to attacks by non-state actors even if there is very little or no state complicity. It is true that Article 51 does not specify that an armed attack must be by a state. But even if there could hypothetically be an armed attack in the absence of state complicity in that attack, the question of the permissible response is much more problematic. For many states and commentators the concept of self-defence against non-state actors was unacceptable before 9/11. Few were willing openly to support a right to use force against a state where the terrorists operated or were present in the absence of the complicity of that state in the terrorist acts.24 The test generally accepted by states was that in the Definition of Aggression, taken by the International Court of Justice in the Nicaragua case as applicable to the concept of armed attack: that the use of force by individuals constituted an armed attack only when there had been a ‘sending by or on behalf of a state of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount to acts of aggression’.25

After 9/11 President Bush announced that the USA would make no distinction between terrorists and those who ‘harboured’ them, and that it would treat any nation that harboured terrorists as a hostile regime.26 Also the Joint Resolution of Congress authorizing force did so against states which ‘planned, authorized, committed or aided the terrorist attacks . . . or harboured such organizations’.27 This has been seen by some as a widening of the right of self-defence. But the USA did not use this language in its letter to the Security Council under Article 51; here it said that it had ‘obtained clear and compelling information that the Al-Qaida organization, which is supported by the Taliban regime in Afghanistan, had a central role in the attacks. . . . The attacks on September 11, 2001 and the ongoing threat to the United States and its nationals posed by the Al-Qaida organization have been made possible by the decision of the Taliban regime to allow the parts of Afghanistan that it controls to be used by this organization as a base of operation’. Despite efforts by the international community the Taliban regime had refused to change its policy. From the territory of Afghanistan Al Qaida continued to train and support terrorists who target US nationals and interests in the USA and abroad.28

The UK argued that Al Qaida was something between a traditional terrorist organization and a state. Osama bin Laden and Al Qaida had been able to commit the atrocities because of their close alliance with the Taliban regime which allowed them to operate with impunity in pursuing their terrorist activity.29 In its letter to the Security Council the UK said that the military action was directed against Osama bin Laden’s Al Qaida terrorist organization and the Taliban regime that was supporting it.30 However, after the event the UK did retrospectively claim that their use of force against Al Qaida and the Taliban in Afghanistan had been undertaken on the basis of a right of self-defence against those who planned and perpetrated large-scale terrorist acts and those who ‘harboured’ terrorists.31

Both states thus left uncertain what degree of involvement, if any, by Afghanistan was necessary to justify the use of force against its territory. Commentators disagree on their interpretation of the facts and of the significance of the language of the USA and the UK. Some have argued that there has been a change in the law to widen it to allow self-defence against states harbouring terrorists;32 others say that such an attempt to widen the law would be impermissible;33 others that on the facts the relationship between Al Qaida and the Taliban regime was sufficiently close to come within the traditional requirements as set out in the Definition of Aggression, even though the USA had used the language of harbouring.34 In this particular case the Security Council had passed repeated resolutions strongly condemning the continuing use of Afghan territory for the sheltering and training of terrorists and planning of terrorist acts, deploring the fact that the Taliban continued to provide a safe haven to Osama bin Laden and demanding that the Taliban regime stop providing sanctuary and training for international terrorists and their organizations.35 Considerable uncertainty thus remains on this long-standing controversy as to the definition of armed attack. Those who argue that the law has changed or should be changed—that the requirements of the Definition of Aggression as applied by the International Court of Justice in the Nicaragua case should be modified in such a way that self-defence may be invoked against non-state actors operating from a state which has tolerated their activities or is unable to control them—have not been able to adduce state practice in support of their argument other than that of Operation Enduring Freedom.36 In so far as their arguments are based on policy considerations they bear the heavy burden of establishing that widening the permissible use of force would be effective in the ‘war on terror’.

As was shown in Chapter 4, the International Court of Justice in the Wall Opinion did not make a clear pronouncement on these questions as to whether there can be an armed attack by a non-state actor and as to what would be the permissible response to such an attack in self-defence.37 Many interpret its brief paragraph on Article 51 as expressly ruling out self-defence against non-state actors. Whether or not the Court took such a categorical position, it clearly adopted a restrictive interpretation of Security Council Resolutions 1368 (2001) and 1373 (2001) in holding that these did not support a claim to self-defence by Israel in this case: ‘The Court also notes that Israel exercises control in the Occupied Palestinian Territory and that, as Israel itself states, the threat which it regards as justifying the construction of the wall originates within, and not outside, that territory. The situation is thus different from that contemplated by Security Council Resolutions 1368 (2001) and 1373 (2001), and therefore Israel could not in any event invoke those resolutions in support of its claim to be exercising a right of self-defence. Consequently, the Court concludes that Article 51 has no relevance in this case.’ Thus the Court treated the applicable law as that of occupation. There could be no right under Article 51 against terrorist attacks originating in the Palestinian territory occupied by Israel.38 In Armed Activities on the Territory of the Congo (DRC v Uganda)—not a case on terrorists, but on opposition groups conducting cross-border attacks—the Court deliberately and explicitly avoided the controversial issue of self-defence against non-state actors in the absence of state involvement in an armed attack.39

Another issue that arises about the scope of ‘armed attack’ after 9/11 is whether it extends beyond attacks on territory to attacks on nationals abroad. Before 9/11 states were divided on this issue.40 The terrorist attacks of 9/11 were on US territory rather than against nationals abroad as they had been in the earlier terrorist episodes discussed above. And the attacks were clearly of a sufficient gravity according to the Definition of Aggression to constitute an ‘armed attack’ under Article 51. Questions must remain as to how far the majority of states would be willing to accept smaller scale terrorist attacks on nationals abroad as giving rise to a right of self-defence against non-state actors in a non-complicit state.

Necessity and proportionality

Another problem arising out of any new right of self-defence against past terrorist actions is the application of the requirement that self-defence be necessary and proportionate. If force is used in response to past attacks, it is not necessary self-defence as the harm has already been done. In so far as self-defence against terrorism is designed to deter and prevent future terrorist acts it is difficult, if not impossible, to employ these central criteria of self-defence in the absence of detailed evidence about a specific threatened attack. The USA and the UK, which both support a wide right of self-defence against imminent attacks, claim that they may take measures proportionate to the threat of a future attack, rather than merely to a specific armed attack which has already taken place.41 This was also the approach adopted by Israel in the 2006 conflict in Lebanon.42 It raises the questions how it would be possible to determine what would be necessary and proportionate to deter a possible, but indeterminate, future attack? If these criteria of necessity and proportionality are not applicable then there are no limits on self-defence. There are more fundamental questions as to how far the use of force is an effective response to terrorism. It is not clear that the forcible response to 9/11 will in fact deter future terrorist attacks: if it is not an effective response, then it could be argued that it cannot be a necessary response.

Operation Enduring Freedom

At the time of writing, Operation Enduring Freedom continues in Afghanistan six years after its inception. Some commentators have expressed doubts as to how far Operation Enduring Freedom is necessary and proportionate, because it started as an aerial bombardment rather than as a more selective ground campaign and because it involved actions not just against Al Qaida but also against the Taliban regime.43 Further questions now arise because the operation has continued for such a long time. It began in October 2001 with an air campaign against fixed targets such as air defence, communication centres and command and control centres, air bases and training camps. It then went on to target the positions of Taliban and Al Qaida forces. At first, the US military campaign operated in cooperation with the Northern Alliance, Afghan opposition forces which had been fighting the Taliban regime in Afghanistan for many years. Together they forced the Taliban to evacuate Kabul in November 2001 and drove them from power. The defeat of the Taliban weakened Al Qaida’s support base in Afghanistan.44

But the political settlement in the Bonn Agreement in December 2001 and the establishment of a UN-authorized force, ISAF,45 in January 2002, to assist the government of Afghanistan in the maintenance of security, did not bring peace or stability to Afghanistan. Military operations by Operation Enduring Freedom continued in pursuit of Al Qaida and Taliban forces; a significant operation in the south was initiated on the same day as action against Iraq began in March 2003.46 The pronouncement by US Defense Secretary Rumsfeld in May 2003 that major combat operations were over has proved distinctly premature.47 ISAF was initially restricted to the area of Kabul until its sphere of operation was extended by Resolution 1510 in October 2003.48 Despite pleas from UN officials and from the President of Afghanistan, the USA was reluctant to accept its expansion beyond Kabul before that date, in case ISAF’s operations interfered with those of Operation Enduring Freedom.49 ISAF’s size and sphere of operation were incrementally increased until it finally extended its area of responsibility to the whole of Afghanistan in October 2006.50 But Operation Enduring Freedom also continues to operate.51

The situation is still unstable, despite the agreement on a new constitution in January 2004, the holding of presidential and parliamentary elections, and the replacement of the transitional Bonn Agreement with the Afghanistan Compact in January 2006.52 The Taliban is resurgent. Insurgent forces increasingly engage in conventional conflicts with Afghan government and international security forces.53 There has also been a growing number of suicide attacks; according to the UN Secretary-General, these represent the most visible link between the insurgency and international terrorism.54 The Security Council has expressed its concern at the increasing violence and terrorist activities in a series of resolutions starting in 2005.55

Much of the country outside Kabul remains lawless, and there have been reports that drug production has increased to record levels.56 In 2002 and 2003 there was factional fighting between various militias and ethnic groups,57 and outside states were reported to maintain support for the different ethnic groups involved in ongoing conflict.58 This factional fighting has now declined but ethnic divisions still affect the country.59 At the end of 2002 Afghanistan concluded a non-aggression pact with its neighbours, China, Pakistan, Iran, Turkmenistan, Uzbekistan and Tajikistan. This was intended to end foreign interference in Afghanistan, something which had contributed to the continuation of 20 years of conflict; the pact was welcomed by the Security Council in Resolution 1453 (2002).60 However, the USA has repeatedly expressed concern that Al Qaida terrorists have fled into Pakistan and are operating from there and it has put pressure on Pakistan’s government to act more strongly against them.61 The USA has also made accusations of Iranian involvement in the insurgency in Afghanistan.62

The USA has involved other states—initially Australia, Poland and the UK—directly in Operation Enduring Freedom in what may be seen as a quest for political legitimacy, even though it has not been willing to accept the constraints of acting through NATO or the UN. Many other states have participated in Operation Enduring Freedom in a support capacity.63 The USA can thus argue that its action is not unilateral but that of a ‘Coalition against Terror’. This search for legitimacy through wider international participation became increasingly important as Operation Enduring Freedom continued, with no express UN basis beyond the initial reference to self-defence in Security Council Resolutions 1368 (2001) and 1373 (2001). The longer Operation Enduring Freedom continues, the further it is detached from its initial basis in self-defence. It may be that awareness of this led to express reference to Operation Enduring Freedom in Security Council resolutions; the first reference was in Resolution 1510 (2003) which called upon ISAF to continue to work in close consultation with the Operation Enduring Freedom coalition in the implementation of its mandate.64 Resolution 1659 (2006) went further and called for ‘closer operational synergy’ between the two forces, and Resolution 1707 (2006) welcomed the increased coordination between them. Also, in Resolution 1589 (2005) the Security Council called on the Government of Afghanistan, with the assistance of the international community, including the Operation Enduring Freedom coalition and ISAF, ‘to continue to address the threat to the security and stability of Afghanistan posed by Al Qaida operatives, the Taliban and other extremist groups, factional violence among militia forces and criminal activities, in particular violence involving the drug trade’.65 These resolutions may be seen as implicit acceptance of the legality of Operation Enduring Freedom by the Security Council, but they contain nothing express on its legal basis, and there was no discussion of this in the Security Council.

In September 2007 the legal basis of the maritime operations conducted by eight states as part of Operation Enduring Freedom did attract some attention in the Security Council. The question apparently arose because there were indications that Japan for domestic political reasons would not agree to continue its navy’s participation in these maritime operations unless there was express Security Council authorization.66 Accordingly, the Security Council in resolution 1776 (2007) extending the authority of ISAF, for the first time made express reference to the maritime operations of Operation Enduring Freedom: ‘expressing its appreciation for the leadership provided by the North Atlantic Treaty Organization (NATO), and for the contribution of many nations to ISAF and to the OEF coalition, including its maritime interdiction component’. Russia abstained on this resolution, because there had been no clarity with regard to the new wording. It said that the activities of the Operation Enduring Freedom coalition were carried out outside the context of the UN, and the Security Council had not been informed in detail about them.67 This indicates an unwillingness to accept the legality of all aspects of the activities of Operation Enduring Freedom.

Initially, perhaps this military campaign in Afghanistan could be seen as a new war against an unprecedented act of terrorism. The USA today maintains that the conflict, like that in Iraq, is the front line in the war on terror.68 But there are many who argue that the conflict in Afghanistan demonstrates that the ‘war on terror’ is self-perpetuating and cannot be won by military means.69 In its prolonged support for an Afghan government unable to retain power on its own against fundamentalist Islamist and ethnic opposition forces, Operation Enduring Freedom seems somewhat reminiscent of the Soviet occupation of Afghanistan from 1979–89. The legal basis of the continuing operations is today left unclear: there is room for doubt as to whether it should still be seen as self-defence against terrorism or whether the authority for the operation now comes from the consent of the new regime in Afghanistan and the fight has become one to secure the stability of the government. The new government established under the auspices of the UN still does not control large areas of its territory and, the longer Operation Enduring Freedom continues, the more questions arise with regard to Afghanistan. The US and UK press releases on the conduct of the campaign give no clear indication on this matter, nor is it discussed in the UN.

Pre-emptive self-defence

Another difficult question arising out of 9/11 and its aftermath is whether self-defence against terrorist attacks is permissible only when there has been an actual past attack or whether a purely pre-emptive action is lawful, and if so, how such a purely pre-emptive action could be necessary and proportionate. Moreover, would pre-emptive action be legal only against terrorism or also against other dangers?

The US letter to the Security Council under Article 51 of the UN Charter said that, ‘In response to these attacks and in accordance with the inherent right of individual and collective self-defence, United States armed forces have initiated actions designed to prevent and deter further attacks on the United States.’70 The UK letter said, ‘These forces have been employed in exercise of the inherent right of individual and collective self-defence, recognized in Article 51, following the terrorist outrage of 11 September, to avert the continuing threat of attacks from the same source.’71 These are claims to preventive and deterrent action which before 9/11 would have been regarded by many as unlawful reprisals rather than lawful self-defence, but even these wide claims were limited by the fact that there had been an actual attack. The apparent attempt by the USA subsequently to extend the right of self-defence to cover purely pre-emptive action has proved extremely controversial.72

How far has Operation Enduring Freedom been a turning point in the law on the use of force?

The operation against Afghanistan can be interpreted in radically opposing ways, as a wide or a narrow precedent in the development of the law on the use of force. On the narrowest view, self-defence would be limited to the situation where there had been an actual massive terrorist attack on a state’s territory, where there was a continuing threat of global terrorism from those responsible and where the response was directed against the organization directly responsible in a state which had allowed it to operate and which then refused to expel it; and then only after the Security Council had determined the existence of a threat to international peace and security; and where the Security Council had asserted a right of self-defence, even if not in the operative part of the resolutions. In the case of Afghanistan, Security Council Resolutions 1368 (2001) and 1373 (2001) could be cited as crucial by states explaining their willingness not to condemn the US action.73

In contrast a wide view of the precedential significance of Operation Enduring Freedom might be asserted whereby states are now free to act in self-defence against the threat of any sort of terrorist attack on their nationals or their territory, even in the absence of any Security Council resolution, and even where the state against whose territory the action is taken had no involvement in any sort of support for the terrorists.


The USA in its letter to the Security Council under Article 51 at the start of Operation Enduring Freedom, having asserted its right to act in self-defence in response to 9/11, went on to say ‘There is much we do not know. Our inquiry is still in its early stages. We may find that our self-defense requires further actions with respect to other organizations and other States.’74 It is not entirely clear whether the USA envisaged action only against those directly involved in the attacks of 9/11 or whether it was already widening the right of self-defence in the war against terrorism. The USA has subsequently gone further, apparently indicating that force may be used even where there has been no actual attack, purely in order to pre-empt future, even non-imminent, attacks. This controversial doctrine is regarded with considerable suspicion by most other states. In 2002 it was initially open to question how far the aim of the USA was really to introduce a radical change in the law or whether the doctrine was designed mainly to stir up fear in certain states, to put pressure on them to modify their behaviour, or to justify targeted killings.75

In his State of the Union Address in January 2002 President Bush said that the ‘war against terrorism’ was just beginning. Although Operation Enduring Freedom in Afghanistan was far from over, he shifted the focus of the war towards the ‘Axis of Evil’ consisting of Iraq, Iran and North Korea. His concern was that these states were developing weapons of mass destruction which they might use themselves or supply to terrorist organizations hostile to the USA. It was with regard to these states that the question of pre-emptive self-defence came to the fore. The USA in September 2002 produced a National Security Strategy in response to the new terrorist threat.76 This was a dramatic document which combined triumph at the victory of the West in the Cold War with alarmism at the threat of terrorism. As President Bush said in his covering letter, ‘Defending our Nation against its enemies is the first and fundamental commitment of the Federal Government. Today, that task has changed dramatically. Enemies in the past needed great armies and great industrial capabilities to endanger America. Now, shadowy networks of individuals can bring great chaos and suffering to our shores for less than it costs to purchase a single tank. Terrorists are organized to penetrate open societies and to turn the power of modern technologies against us.’ The 2002 National Security Strategy warned, ‘While the US will constantly strive to enlist the support of the international community, we will not hesitate to act alone if necessary, to exercise our right of self-defense by acting pre-emptively against such terrorists, to prevent them from doing harm against our people and our country.’

The third US goal in the 2002 National Security Strategy was to strengthen alliances to defeat global terrorism and to work to prevent attacks against us and our friends. The aim was to disrupt and destroy terrorist organisations, to identify and destroy the threat before it reached their borders. This third goal was linked to the fifth, to prevent our enemies from threatening us, our allies and our friends with weapons of mass d estruction. This link between states developing weapons of mass destruction—the US singled out Iraq and North Korea in this regard—and terrorists was used further to extend the right of self-defence. The USA was now putting forward a new ‘Bush doctrine’, extending the right of self-defence far beyond its traditional scope. The USA must be prepared to stop rogue states and their terrorist clients before they are able to threaten to use weapons of mass destruction. ‘Given the goals of rogue states and terrorists, the US can no longer rely on a reactive posture as we have in the past. The inability to deter a potential attacker does not permit that option. We cannot let our enemies strike first . . . We must be prepared to stop rogue states and their terrorist clients before they are able to threaten or use weapons of mass destruction against the US. The doctrine of self-defence needs to be revised in the light of modern conditions. In particular the requirement that a threat be imminent needs to be revisited.’ The USA asserts that pre-emptive self-defence has been recognized for centuries, a controversial claim in the light of the divisions between states on this subject.77 But even this is not enough: the USA now argues that circumstances have changed and that the requirement of imminent attack should be adapted to the capabilities and objectives of today’s adversaries.

This argument was repeated by President Bush in his 2003 State of the Union Address, with express reference to Iraq, when he said, ‘Some have said that we must not act until the threat is imminent. Since when have terrorists and tyrants announced their intentions, politely putting us on notice before they strike? If this threat is permitted to fully and suddenly emerge, all actions, all words, and all recriminations would come to late. Trusting in the sanity and restraint of Saddam Hussein is not a strategy and not an option.’78

This apparent attempt to extend the war against terrorism to cover purely pre-emptive action in the absence of an imminent threat provoked much controversy.79 President Bush seemed to be taking advantage of the rhetoric of the ‘war against terrorism’ and the legitimacy conferred by that war to stretch the boundaries of self-defence.80 There is some uncertainty as to the exact scope of the US claims. The terms anticipatory, preventive and pre-emptive are not technical terms of art with clear meanings and they are used in different ways by different authors. But the crucial question of substance is whether the USA is claiming a right to use force against non-imminent threats. This was certainly the impression given by President Bush in the speech quoted above. And this was the UK Attorney-General’s understanding of the US position. In his advice on the legality of the use of force against Iraq, he said, ‘I am aware that the USA has been arguing for recognition of a broad doctrine of a right to use force to pre-empt danger in the future. If this means more than a right to respond proportionately to an imminent attack (and I understand that the doctrine is intended to carry that connotation) this is not a doctrine which, in my opinion exists or is recognized in international law.’81

Whereas states did not challenge the legality of Operation Enduring Freedom, there is little sign of any willingness by states to abandon the requirement that for self-defence to be permissible a terrorist attack should already have occurred, be underway, or at the most extensive, be imminent. The opposition by many states to Operation Iraqi Freedom (which started in March 2003) made it clear that they were not willing to accept pre-emptive self-defence as a legal basis for that particular action.82

The High-level Panel Report and the Secretary-General’s Report In Larger Freedom both expressly rejected the doctrine of pre-emptive self-defence which they understood as action against non-imminent threats. These reports addressed the issue whether the right of self-defence should be expanded to meet the new threats facing the world. Although both reports controversially accepted anticipatory self-defence against an imminent attack, they were not prepared to go any further. Where the threat is not imminent—for example, the acquisition of nuclear weapons-making capacity—a state cannot act pre-emptively against a non-imminent or non-proximate threat. In such a situation it was for the UN Security Council to authorize action. Unilateral pre-emptive action posed too great a threat to global order.83 Nor was there any widespread support by states for the US doctrine.84

Nevertheless the USA strongly rejected the position of the High-level Panel Report: ‘Given today’s threats we should not be putting new constraints on self-defence. But that is what would happen if the proposal that only the Security Council could authorize the prevention of the use of force were adopted. Even in cases where terrorists have a nuclear weapon, the report says that a state should go to the Security Council first for authorization to take preventative military action . . . Such constraints will never be acceptable to the United States.’85 And in 2006 the USA issued a new National Security Strategy. In this it repeated its commitment to pre-emptive self-defence.86 It said, ‘The place of pre-emption in our national security strategy remains the same’ and it reaffirmed all the relevant sections of the 2002 Strategy on the use of force. But its identification of the nature of the threat in the war on terror had shifted since 2002: the main danger was now said to come not from shadowy networks of individuals but from ‘Islamic extremists’,87 and it was now Iran and Syria (rather than Iraq and North Korea) which posed the greatest threat as ‘sponsors of terror’.88

The 2006 Strategy, like its predecessor, leaves many questions about pre-emption unanswered. It does not make clear what will trigger the right of pre-emptive action and what is the proper scope of such action. It repeats the words of the 2002 Strategy that ‘under long-standing principles of self-defence we do not rule out the use of force before attacks occur, even if uncertainty remains as to the time and place of the enemy’s attack’,89 and adds only that, ‘The reasons for our actions will be clear, the force measured, and the cause just.’ There is no further discussion of the imminence requirement. Indeed there is no mention of international law in the 2006 Strategy and almost no mention of the role of the UN in the maintenance of international peace and security.

There is very little international support for this doctrine of pre-emptive self-defence.90 The General Assembly debates on In Larger Freedom showed that most states were not willing to accept anticipatory, let alone pre-emptive self-defence.91 The 118 member Non-Aligned Movement has repeatedly rejected the doctrine of pre-emptive self-defence.92 NATO, which had been given only very limited mention in the 2002 and the 2006 US National Security Strategy, has not openly adopted the Bush doctrine of effectively unlimited self-defence. It is in the process of trying to re-define its role after the end of the Cold War, and in the light of 9/11.93