The June 2002 Bush Doctrine and the September 2002 National Security Strategy of the United States of America (NSS) brought the issues of preemption and prevention in the use of force to the fore in international relations. In both the Bush Doctrine and the NSS, the United States attempted to deal with three types of new interconnected threat: terrorist groups, weak states and rogue states. Both documents promised to confront global terrorism and to hold to account nations compromised by terrorism, including those that harbour or support terrorists by compelling such states to accept their sovereign responsibilities. 1 The United States declared that it would seek to prevent the activities of rogue states and their terrorist clients before they were in a position to threaten, or to use, weapons of mass destruction (WMD). The NSS stated that, in order ‘to forestall or prevent such hostile acts [we will], if necessary, act pre-emptively’. 2
This article examines the right of a state’s self-defence under international law against the emergence of non-state threats and the rise of pre-emption and prevention. It seeks to explain the differences between pre-emptive and preventive military action in customary international law. The article also tries to demonstrate the complexity of self-defence in an age of transnational terrorism and outlines the emergence of new theories such as interceptive attack and sufficient threat, which have attempted to align ‘anticipatory self-defence’ with the new realities of international security.
Self-Defence, Pre-Emption and Prevention
In order to understand arguments surrounding pre-emption and prevention, it is necessary to examine briefly the idea of self-defence under the United Nations (UN) Charter. Under Article 51 of the UN Charter, a state is given ‘an entitlement to use armed force in order to defend itself against an attack, to repel the attackers, and to expel them from its territory’. 3 Most states recognise that self-defence within international law must meet two conditions: necessity and proportionality. The latter condition is often described as the ‘essence of self-defence’.4 For example, in 1996, in its advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, the International Court of Justice reaffirmed the importance of the principles of both necessity and proportionality. The Court noted that these dual conditions represent ‘a rule of customary international law’ that ‘applies equally to Article 51 of the Charter’. 5
If necessity and proportionality continue to be the yardsticks of legitimate self-defence, how do they apply to self-defence by pre-emption and prevention in an age of non-state terrorism and WMD proliferation? At what point should a state use force pre-emptively or preventively? Can a state seek to limit damage on itself by acting in advance of a planned attack? First, we must identify the differences between pre-emption and prevention. Pre-emptive self-defence involves the initiation of military action based on a perceived imminent attack and identifies clear advantages in striking first. 6 Preventive self-defence, on the other hand, may be regarded as the use of force by a state in order to avoid the risk of war occurring later under less favourable circumstances. Jack Levy has identified four differences between pre-emption and prevention.7 First, while pre-emption is usually a tactical response to an immediate threat, prevention tends to be a strategic response to a longer-term threat, or to one that has yet to develop. Second, a pre-emptive attack is designed to forestall deployment of existing forces or weapons. Prevention, on the other hand, aims to halt the development of new forces or new weapons systems.
Third, in pre-emption, it is the imminent risk of attack by an adversary that leads a state to take military action against that adversary. In contrast, prevention is caused by the gradual deterioration of a state’s relative military power and the strategic risk that such a deterioration creates. Finally, the incentives to strike first are different in pre-emption and prevention. In pre-emption there is a perceived incentive to strike first. In prevention the incentive to strike first is not necessarily present. Instead, preventive attack may become feasible because of the ‘margin of safety provided by the preventer’s own military superiority’. 8
In general terms, the anticipatory use of force is usually viewed under the rubric of preemption based on a notion of an imminent threat. In this respect, Article 51 and Article 2 (4) of the UN Charter have been influenced by the rules of pre-emptive war in customary international law laid down by the famous 1837 Caroline doctrine. In a dispute with Britain over the use of force against Canadian rebels on American soil, US Secretary of State, Daniel Webster, enunciated in 1837 a doctrine of anticipatory self-defence. The latter was based on an imminent threat that was ‘instant, overwhelming and leaving no choice of means and no moment for deliberation’.9 Pre-emptive attack may be a legitimate form of self-defence provided action is clearly linked to a defined threat of aggression. In O’Brien’s words,
if there is a clear and present danger of aggression ... military coercion may be employed not only to repel but also to prevent imminent illegal military coercion and, if necessary, to attack the proximate sources of recurring illegal military coercion. 10
The legal case for and against anticipatory self-defence remains contentious, however. A literal reading of Article 51 may yield a clear argument that the right of self-defence arises only if an ‘armed attack’ occurs. Most scholars who favour a restrictive interpretation of self-defence believe that a broad interpretation of Article 51 would provide states with an opportunity to violate the rules prohibiting the use of force. 11 A wider reading of Article 51, however, suggests that, by reference to the ‘inherent right’ of self-defence, the UN Charter preserves the earlier well-defined customary right to pre-emptive self-defence. According to a broad interpretation, Article 51 highlights only one form of self-defence—namely response to an armed attack—and does not negate other legitimate actions in self-defence under customary international law. 12 For instance, in his dissenting opinion to the 1986 Nicaragua case at the International Court of Justice, Judge Schwebel rejected a reading of Article 51 that implied that the right of self-defence existed ‘if, and only if, an armed attack occurs’. 13
Since 2001, the UN Security Council has, in various resolutions, also reaffirmed the ‘inherent right’ of states to act in self-defence against terrorism. In resolutions 1368 and 1373, the council has pronounced that states ‘shall take the measures necessary to prevent the commission of terrorist acts’. 14 These two resolutions support previous debates in the Security Council that ‘the right of self-defence is not an entirely passive right’. Since terrorism involves assaults by small groups employing irregular and ‘hit and run’ tactics, it can be argued that a series of ‘pin-prick’ assaults might be weighed in their totality and count as an actual ‘armed attack’ under the accepted UN definition. 15
Interceptive Attack and Sufficient Threat
In addition, the UN General Assembly’s Definition of Aggression refers to the first use of force as constituting only prima facie evidence of aggression. Preparation for an armed attack may long precede the actual firing of the first shot and may legally justify a response. Seen from this perspective, then, the use of force by a state acting in self-defence is not so much anticipatory as interceptive in character. The notion of interceptive self-defence is an interesting one. Dinstein defines interceptive self-defence as taking place ‘after the other side has committed itself to an armed attack in an ostensibly irrevocable way’. 16 Under new security conditions, the concept of interceptive attack presents a useful and alternative way of reformulating the right of self-defence in international law. When considered together with wider definitions of what constitutes armed attack—notably the 11 September 2001 attacks on the Pentagon and the World Trade Center—interceptive self-defence may present a legitimate way for states to respond to terrorism lawfully, even under the limitations of Article 51 of the UN Charter. 17
Alongside the idea of interceptive self- defence, Michael Walzer has argued that, for states dealing with the threat of aggression, an exact line between legitimate and illegitimate first strikes should not ‘be drawn at the point of imminent attack but at the point of sufficient threat’. 18 Using the concept of sufficient threat, Walzer has made an important distinction between pre-emptive and preventive war. He argues that prevention—lying on the far end of the ‘anticipation spectrum’—is a strategy of attack that responds to a ‘distant danger’. The motivation for preventive war is likely to be linked to the balance of power between states and may not always meet the conditions of sufficient threat that are required to justify the anticipatory use of force.
Indeed, international terrorism may justify the use of pre-emptive force in order to nullify ‘sufficient’ threat. As Walzer notes, ‘perhaps the gulf between pre-emption and prevention has now narrowed such that there is little strategic, and therefore little moral, difference between them’. 19
The use of force against an adversary before the outbreak of hostilities may be justified if a state is facing what Walzer terms a ‘supreme emergency’ during which the very existence of the community of citizens may be at stake. A supreme emergency involves danger beyond ‘ordinary war’, and both its imminence and apocalyptic character may ‘well require exactly those measures that the war conventions bar’. 20 The ongoing problem of a global terrorist threat could also meet the requirements for exceptional ‘imminence’ in order for pre-emptive or preventive actions to be justified during a supreme emergency.
An offensive war by a state against an adversary that presents a clear and present danger, or one that threatens the values and interests of the international community, could be morally permissible and justified as a ‘necessary war’ of individual or collective self-defence. In this context, Michael O’Keefe has proposed that ‘international terrorism could represent a threat to the existence of a state if weapons of mass destruction were used, [and] it could be argued that [such a threat] would represent a supreme emergency’. 21 Given the scope of recent international terrorist activity and the problems associated with curtailing global WMD proliferation, this approach would indeed seem to encompass Walzer’s criteria for both exceptional ‘imminence’ and the ‘nature’ of any given threat. Legal support for pre-emptive strategies is not an extension to the scope of self-defence, but is based on a belief that the lawfulness of any use of force against terrorist organisations should rest on a wider interpretation of the definition of armed attack.
Conclusion
In an age of terrorism, the pre-emptive and preventive strategies of recent US policy represent attempts to deal effectively with new threats to national and international security. The work of such scholars as Dinstein and Walzer on when and how force can be used as an interceptive instrument or at a time of sufficient threat also demonstrates the complexity of developing new rules to deal with non-state threats. It remains important that states seek to legitimise the use of force according to the mutually reinforcing traditions of ethics and international law. As Oscar Schachter writes, the basic premise of international law governing the use of force must be that ‘the right of self-defence, inherent though it may be, cannot be autonomous. To consider it as above or outside the law renders it more probable that force will be used unilaterally and abusively’. 22
International terrorism straddles both crime and war, and threatens not so much territorial borders but the inherent rights of a state’s citizens. Such a threat is difficult to deal with according to conventional interstate norms. ‘When states are attacked’, Walzer reminds us, ‘it is their members who are challenged, not only in their lives, but in the things they value most, including the political association they have made’. 23 In the past the threat to states was unambiguous; in the early 21st century this situation has changed. In an era of transnational and non-state threats, it should come as no surprise that the international community is faced with a range of new legal and ethical challenges stemming from the rise of pre-emption and prevention.
Endnotes
1 For the Bush Doctrine see The White House, ‘President Delivers Graduation Speech at West Point’, 1 June 2002, <http://www.whitehouse.gov/news/releases>; The National Security Strategy of the United States of America, The White House, Washington, DC, September 2002, p. 6.
2 The National Security Strategy of the United States of America, pp. 14–15.
3 R. J. Jennings and A. Watts (eds), Oppenheim’s International Law, vol. I, 9th edn, Longman, New York, 1996, pp. 417–18.
4 I. Brownlie, International Law and the Use of Force by States, Clarendon Press, Oxford, 1963, p. 279.
5 C. Gray, International Law and the Use of Force, Oxford University Press, Oxford, 2000, p. 106.
6 Bernard Brodie, Strategy in the Missile Age, Princeton University Press, Princeton, NJ, 1959, pp. 225; 241.
7 J. Levy, ‘Declining Power and the Preventive Motivation for War’, World Politics, October 1987, vol. 40, no. 1, p. 82.
8 Ibid., pp. 90–2.
9 R. Y. Jennings, ‘The Caroline and McLeod Cases’, American Journal of International Law, 1938, vol. 32, no. 1, pp. 82–99.
10 W. V. O’Brien, The Conduct of Just and Limited War, Praeger Publishers, New York, 1981, p. 26.
11 Yoram Dinstein, War, Aggression and Self-Defence, 3rd edn, Cambridge University Press, Cambridge, 2001, pp. 165–9; Gray, International Law and the Use of Force, pp. 96–105.
12 A. C. Arend, ‘International Law and the Preemptive Use of Military Force’, The Washington Quarterly, Spring 2003, vol. 26, no. 2, pp. 90–3.
13 Dinstein, War, Aggression and Self-Defence, p. 168.
14 P. Rowe, ‘Responses to Terror: The New War’, Melbourne Journal of International Law, 2002, vol. 3, pp. 301–22.
15 Dinstein, War, Aggession and Self-Defence, p. 192; Gray, International Law and the Use of Force, pp. 107; 117.
16 Ibid., p. 172.
17 Gray, International Law and the Use of Force, p. 112.
18 Michael Walzer, Just and Unjust Wars: A Moral Argument with Historical Illustrations, 3rd edn, Basic Books, New York, 2000, p. 81.
19 Ibid., pp. 75–80.
20 Ibid., pp. 228; 251–2.
21 M. O’Keefe, ‘Terrorism and the Right to Wage War’, in T. Coady and M. O’Keefe (eds), Terrorism and Justice: Moral Argument in a Threatened World, Melbourne University Press, Melbourne, 2002, p. 108.
22 O. Schachter, ‘The Right of States To Use Armed Force’, Michigan Law Review, 1984, vol. 82, p. 277.
23 Walzer, Just and Unjust Wars, p. 53.
