By: Dharmil Doshi, SVKM’s Pravin Gandhi College of Law, Mumbai University.

ABSTRACT This work deals with only the interpretation and the criteria about Anticipatory Self-Defence limited to the mentioned Treaty Law only from a theoretical-legal aspect. This article does not give examples of State Practice and customary International Law holistically. The few examples, illustrations or cases used serve as evidence or complimentary to the point raised, rather than indicate any State Practice or opinio juris.

The primary Treaty Law corresponding to a State’s right to self-defence against the use of force is Article 51 of the United Nations Charter[1] in coherence with Article 2(4) of the Charter. Article 51 of the Charter states that: “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. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.” At the outset, for the prima facie analysis of the concept of anticipatory self-defence under Article 51, the provision of Article 31(1) of the 1969 Vienna Convention on the Law of Treaties[2] must be taken into account: “A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose.” In perspective, Article 51 is interrelated  to Article 2(4) of the Charter “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 the United Nations.”

In light of the aforementioned, it goes without saying that one of the most controversial, yet forefront issues of International Law is concerning this right of self-defence. There is a general tendency to respect the right of self-defence as an inherent right of nation states in view of the Westphalian Nation-State System which is marked by the absence of a common sovereign authority. As a result, nations states, who are sovereign equals, must have a right to self-defence to protect and promote their national interest.

The crux of the question inquires if this right may be exercised only once an armed attack has commenced or occurred, or if a State threatened with an armed attack may take action to forestall or address it.

Anticipatory self-defence has its roots in the standard established in the famous 1837 Caroline case, where British soldiers crossed the Niagara River in Canada and attacked the American steamship Caroline that was aiding the Canadian rebels.[3] Britain insisted that they acted in self-defence, but the then-Secretary of State Daniel Webster wrote in correspondence with the British government that the use of force prior to suffering an attack qualifies as a legitimate self-defence only when recourse to act is “instant, overwhelming, and leaving no choice of means, and no moment for deliberation.”[4]

The question on hand has led to extensive deliberation deciphering itself in literature about anticipatory self-defence and other closely related notions including pre-emptive action, and other forms of preventative or interceptive measures. However, none of these terms have any definite legal meaning for composite interpretation, and consequently, different commentators have attributed different meanings to them. Primarily there are two schools of thought concerning the interpretation of this right, being the restrictive and the expansionist.


The restrictive school propounds that the UN Charter would have provided more detail on the anticipatory nature of self-defence if it intended to outline its legitimacy. Anticipatory self-defence, if legitimate under the Charter, “would require regulation by lex scripta[5] more acutely than a response to an armed attack since the opportunities for abuse are incomparably greater.”[6]

To set the premise, it is argued that “Self-defence” is an expression that entails a situation or de facto condition, not a subjective “right”. [7] The restrictive school further stipulates that a government could deliberately portray its adversary as being positioned to attack to gain a carte blanche for aggression under the flag of anticipatory self-defence.[8] They fear   nation “can use the right of self-defence to justify virtually any aggressive action.”[9] The sentiment emerges that the possibility of abuse is not a sufficient ground to discount the existence of the right.[10]

However, this possibility of abuse is considered not as a sufficient ground for the denial of the exercise of anticipatory self-defence by the expansionists.


The expansionist school tends to focus on the wording “inherent right”.[11] They hold the view that a State shall not wait for an attack to breach its territory for under the Charter, every sovereign nation-state has the right to maintain and defend its territory and also imposes an obligation on other states to respect each other’s territorial integrity.[KR1]  The traditional self-defence paradigm dictates that the introduction of the Charter and Article 51 has not abrogated the pre-existing customary right of self-defence which enabled a State to respond to imminent attacks. The Nuremberg Military Tribunal has affirmed when adjudicating upon the invasion of Denmark and Norway “It must be remembered that preventive action in foreign territory is justified only in case of an instant and overwhelming necessity for self-defence, leaving no choice of means, and no moment of deliberation.”[12]

If a State waits for an armed attack, it will then become responsible for the restoration, instead of maintenance, of international peace and security.[13]

Over a period of time, a number of criteria as discussed below seem to have evolved regarding the exercise of anticipatory self-defence.

The essential preconditions of “self-defence in general” include fulfilment of “necessity, “proportionality” at the foremost complemented by “immediacy.”‘[KR2] [14] The ICJ has held in the Nicaragua Case[15] that “there is a specific rule whereby self-defence would warrant only measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary international law.”[16]

The State threatened with an imminent attack shall not, in the particular circumstances, have any alternate means of halting or defusing the attack other than recourse to armed force. The decision employing force under the banner of anticipatory self-defence is one which is generally conditioned reflex to stress.[17] The arguable “doctrine” of anticipatory self-defence would require a symmetry or an approximation between the relevant action and its purpose, the latter being that of preventing the occurrence of an armed attack.

A pertinent factor to ponder in correspondence to the proportionality test is the nature of the weapon. The ICJ in its 1996 Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons did not rule out the possibility of resort to nuclear weapons “in an extreme circumstance of self-defence, in which the very survival of a State would be at stake.”[18]

If, however, the threat or the attack comprises of a number or series of successive acts, and there is adequate reason to expect a continuation of similar acts from the same identified source, the immediacy as well as the proportionality criteria should be viewed as a whole.[19] Use of force against such an attack would be one of anticipatory self-defence and not of reprisal, since its primary motive would be protective, not punitive in the grand scheme of the circumstances[20]. On the contrary, it is a well-established principle in International Humanitarian Law that attacks by way of reprisal for revenge or as a penalty are unlawful.[21]

A Chatham House study[22] propounds that “The criterion of imminence requires that it is believed that any further delay in countering the intended attack will result in the inability of the defending State effectively to defend itself against the attack” and comments that “in this sense, necessity will determine imminence: it must be necessary to act before it is too late.”[23] Further, the UN High-level Panel on Threats, Challenges and Change stated in 2004 without further qualification that ‘a threatened State, according to long established international law, can take military action as long as the threat is imminent, no other means would deflect it and the action is proportionate.’[24]

The exercise of the above notion has been criticized by the member States of the “Non-Aligned Movement”. In the Congo v Uganda decision of 2005, the ICJ limited itself to formulating a critical obiter dictum against basing military action on ‘essentially preventative’ security needs, but it noted at the same time that ‘the issue of the lawfulness of a response to the imminent threat of armed attack has not been raised’.[25]

After understanding these requirements in the exercise of such a right, one should note the distinction of Anticipatory from Pre-emptive self-defence. The latter tends to have a longer time frame where a State often views the target or adversary’s particular, tangible actions as certainly emerging into an armed attack against it. Pre-emptivee self-defence prompts the State to halt such a development of future threat, often without acquiring precise information concerning where or when the attack might occur. Often, pre-emptive self-defence is resorted to even in the lack of specific evidence of the adversary’s capacity or intent to attack. States such as the USA have deliberated upon the synonymity of pre-emptive and anticipatory self-defence, enunciating its legitimacy.[26]

ROLE OF UNSC IN ARTICLE 51:  Article 51 in a way recognises the primary responsibility of the United Nations Security Council to maintain international peace and security as the enforcement organ of the United Nations. . The [KR3] recognition for a State acting in anticipatory self-defence may diminish, under the system envisaged by the Charter, as soon as the UNSC took it upon itself to employ the enforcement measures under Chapter VII of the Charter.  However, if such an affirmative action of the UNSC is impeded, delayed, or inadequate and the armed attack at hand becomes manifestly imminent, then it would be a travesty of the purposes of the Charter to compel a defending state to allow its assailant to deliver the first and perhaps fatal blow. [27]

MILITARY ACTION AGAINST NON-STATE ACTORS/ TERRORISTS:A significant aspect here is the use of armed force against violent non-state actors under the banner of anticipatory self-defence, which has been one of the most intriguing evolutions of State Practice after the twin-tower attacks of 9/11 and the evolution of the Bush Doctrine.[28] The [KR4] burden of proof must be[KR5]  high in the event of military action against violent non-state actors. Most of the violent non-state actors, especially International terrorist organisations tend to operate with a nexus with one sovereign State or the other. In fact, it is not always but often there is a strong evidence to suggest States harbouring or providing safe havens to such organisations for their endeavours. However, the sponsoring States tend to invoke the defence of breach of territory or intervention in domestic matters to restrict anticipatory attacks against these non-state actors. At the same time, anticipatory self-defence against non-state actors can be taken as a pretext to violate the territorial integrity of another State. Against this background, the launching of anticipatory self-defence against such non-state actors is left unchecked, creating a dangerous lacuna. The credible evidence that its action has met the conditions required must be presented to the satisfaction of the competent international bodies, primarily the UNSC and the UNGA.

How a State legally accounts for its actions of anticipatory self-defence, affects the legitimacy that fellow states tend to afford to the State generally and particularly to its action.[KR6] . The evolving State practice suggests the shifting or potential shift from the restrictive position towards a more permissive one.[29] Moreover, for the time being, a State that uses force in anticipatory self-defence might be able to calibrate its action such that it falls in a legal grey zone—in which it foregoes the legitimizing effect of having the law on its side but also avoids the verbal or material blowback of a violation.[30].

The right of anticipatory self-defence, although subjectively postulated, certainly is of immense virtue. In a world without a common sovereign body that could prevent powerful aggressor states from acting at free will, it becomes an ipso facto prerogative of a State to preserve its right or rather defence of employing force in reasonable anticipation. However, “without the sine qua non[31] of necessity, proportionality, and immediacy, anticipatory self-defence becomes nothing more than a slippery slope of naked aggression.”[32]

[1] Charter of the United Nations (adopted 24 October 1945) 1 UNTS XVI

[2] United Nations Vienna Convention on the Law of Treaties (23 May 1969) 155 UNTS 331

[3] Alex Potcavaru, The International Law of Anticipatory Self-Defence and U.S. Options in North Korea ( Lawfare Blog, 8 August 2017) <> accessed 26 November 2020

[4] Letter of Mr. Webster to Mr. Fox (April 24, 1841), in 29 BRITISH AND FOREIGN STATE PAPERS, 1840-41 at 1137-38 (1857)

[5] Law authorized or created by statute rather than custom or usage, Black’s Law Dictionary (8th ed. 2004)

[6] Yoram Dinstein, War, Aggression and Self-Defence (Cambridge University Press 3d ed. 2001) 167

[7] Roberto Ago, Addendum to the 8th Report on State Responsibility (1980 2 Y.B. Int’l L. Comm’n 52) 53

[8] Romana Sadurska, Threats of Force (82 AM. J. INT’L L) 239

[9] Byard Q. Clemmons & Gary D. Brown, Rethinking International Self-Defence: The United Nations’ Emerging Role (45 NAVAL L. REV. 217, 234, 1998) 223

[10] Van de hole, Leo. “Anticipatory Self-Defence Under International Law.” American University International Law Review 19, no. 1(2003): 69-106, at 87

[11] V.A.V Andreas ‘Anticipatory self-defence in international law: legal or just a construct for using force?’ (ANR 267515) <>  accessed 27 November 2020.

[12] Judgment of the International Military Tribunal (Nuremberg), 1 October 1946, reproduced in (1947) 41 AJIL 172–333, at 205.

[13] Richard J. Erickson, Legitimate Use of Military Force against state-sponsored International Terrorism, 139

[14] Supra fn. 6 at 68

[15] Case Concerning Military and Paramilitary Activities (Nicaragua v U.S.A), [1986] (I.C.J. 14) (June 27)

[16] Ibid at 94

[17] Mark E. Newcomb, On-Proliferation, Self-Defence, and the Korean Crisis (1994 27 VAND. J. TRANSNAT’’L) 621

[18] Legality of the Threat or Use of Nuclear Weapons [1996] (I.C.J. 244 (July 8) para. 105(2)E

[19] Supra fn. 6 at 70

[20] Report of the Committee on Use of Force in Relations Among States (1985-86 AM BRANCH OF THE INT’L LAW ASS’N) 206

[21] Additional Protocol I of 1977 to the Geneva Convention of 1949, Article 51(8)

[22] The Chatham House Principles of International Law on the Use of Force in Self-Defence by Wilmshurst, Elizabeth [(2006) 55(4) ICLQ 963]

[23] Ibid at 968

[24] UNGA ‘A More Secure World: Our Shared Responsibility, Report of the High-level Panel on Threats, Challenges and Change’ (2 December 2004) UN Doc A/59/565, para 188.

[25] Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda) [2005] ICJ Rep 168, para 143.

[26] Ibid

[27] Claud H.M. Waldock, The Regulation of the Use of Force by Individual States in International Law (1952 II RECUEIL DES COURS 451) 496-97

[28] The policy announced by President George W. Bush after the September 11, 2001 attacks on the World Trade Center and the Pentagon, to the effect that nations harbouring terrorists will be treated as terrorists themselves and may be subject to a first-strike strategy, Black’s Law Dictionary (8th ed. 2004)

[29] Monica Hakimi ‘North Korea and the Law on Anticipatory Self-Defence’ (28 March 2017) EJILT <>  accessed 26 November 2020

[30] Monica Hakimi ‘North Korea and the Law on Anticipatory Self-Defence’ (28 March 2017) EJILT < > accessed 26 November 2020

[31] An indispensable condition or thing; something on which something else necessarily depends, Black’s Law Dictionary (8th ed. 2004)

[32] Michael Lacey, Self-Defence or Self-Denial: The Proliferation of Weapons of Mass Destruction (10 IND. INT’L & COMP. L. REV) 294




 [KR4]The link has repetition of words



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