Aggression, from Cyber-Attacks to ISIS: Why International Law Struggles to Adapt

Albi Kocibelli
Vol. 39 Editor In Chief

Ius ad bellum and the notion of aggression have been a ‘yin yang’ for centuries.[1] Nevertheless, international law did not prohibit states from engaging in aggression until the conclusion of the Kellogg-Briand Pact.[2] Even then, the term was not defined.  In the aftermath of World War II, the act of aggression was equated with ‘waging of war’ by the Nuremberg Tribunal.[3] Twelve defendants were convicted of that crime.[4] The trial constitutes the fundamentals of the modern understanding of aggression. The term is used twice in the UN Charter. Paragraph 1 of Article 1 lists as one of the Charter’s purposes “the suppression of acts of aggression or other breaches of the peace.” Article 39 empowers the Security Council to determine which acts constitute aggression. However, aggression is nowhere defined in the Charter. Instead, it imposes a general prohibition on the use of force in Article 2(4)[5] and exceptions under Article 51[6] and Chapter 7.[7] 

In order to help the Security Council, faced with a definitional void, effectively carry out its duty under Article 39, the General Assembly promulgated Resolution 3314 as a guide for the political organ of the UN.[8] The resolution defined aggression as a violation of the use-of-force rules of Article 2(4) and laid down several acts that might constitute prima facie evidence of an act of aggression.[9] Moreover, Article 4 provided that the acts enumerated were not exhaustive and that the Security Council could determine other acts that constituted aggression under the Charter.[10] This has been the framework, under which both the ICJ[11] and scholars[12] elaborated issues of ius ad bellum and aggression. The Rome conference in 1998, while establishing the ICC, failed to provide anything new in defining acts of aggression. An accord on the definition was finally reached in 2010 in Kampala. The agreed definition incorporated in toto the acts specified in Article 3 of Resolution 3314.[13] As this article tries to point out, limiting the definition to a mere incorporation instead of developing a new definition is likely to have major negative repercussions.

So why should an additional treaty be a problem and not a relief in clarifying the law? The simple answer lies in the Baxter paradox. In his 1970 lecture at The Hague Academy of International Law, while analyzing the interplay between treaty and custom, Richard Baxter pointed out the unwelcome side effects the treaty making process could have.[14] In particular, he noted that treaties declaratory of custom, while clarifying the law, may halt the further development of custom. As a result, “until the treaty is revised or amended the customary international law will remain the image of the treaty.”[15] In this context, the Kampala amendments pose several implications.

Initially, it should be noted that the incorporation in toto of Article 3 of Resolution 3314 into the Kampala amendments per se affirms the point made by Baxter: Once codified, customary international law inhibits the subsequent development of the law. If a General Assembly resolution, considered by some to be soft law and criticized for being too vague,[16] has such an effect, more is to be expected from the Rome Treaty. Moreover, while the former, meant as a guideline for the Security Council and not as a binding instrument among states, provided flexibility by allowing the Council to determine other acts that might constitute aggression, the latter restricts the international community to an exhaustive list compiled in the 70’s. This list, stipulated at the time in a state-centric Cold War mentality, not only does not mention non-state actors, but is also alien to emerging trends such as cyber-attacks. It has become clear that in certain circumstances, such attacks might constitute a use-of-force within the meaning of Article 2(4) and customary international law.[17]

Several countries have been prone to cyber-attacks of different magnitudes,[18] and some of them like the US have incorporated the term as part of their national security.[19] Experts generally agree that potential cyber-attacks in the near future, whether conducted by state or non-state actors, are likely to carry significantly greater consequences than traditional warfare.[20] As enumerated by Murphy,  hypothetical targets might include the disabling of water purification systems, misrouting of traffic causing massive collisions, the intentional opening of dams, or even the meltdown of nuclear reactors.[21] Moreover, the recent alleged Russian cyber-attack aimed at undermining the 2016 Presidential Elections in the U.S. seems to have escalated the debate. Members from both major parties have voiced their concerns, and some have gone as far as to equalizing the cyber-attacks to an act of war. Same demands have been articulated by other NATO members as well.

At this point, a natural question would be whether it can be expected from the ICC to play a gap filling role. The short answer: No. As Reisman points out, “different legal jobs use entirely distinct modes of making principled decisions.”[22] The legitimacy of the court will depend on the consistent and “correct” application of the statute, and thus the “principles of interpretation of texts and other verbal formulations that lay claim to some authority are virtual articles of faith.”[23]

The ICJ has been haunted by the same problem since its inception as well. All are witness of the difficulties the court has faced in Armed Activities[24] and the Wall[25]opinion in dealing with the use of force by non-state actors. Many have criticized the ICJ for operating within its own small world. In an age when non-state actors are becoming more relevant the ICC, or for that part any other tribunal, assuming that no other war crimes are committed, would have more than a tough time in dealing with organizations like ISIS or the current situation in Syria and Iraq in terms of aggression.

Thus, the Kampala amendments, by relying on traditional or even outdated concepts rather than the consequences of the committed acts, are wanting in defining aggression per se. Consequently, the amendments would crystallize international customary law in their own vague and ill-drafted image. Given the fact the negotiation process is highly political, it would be almost impossible to reach a new compromise and an improvement of the definition by new amendments. To be fair, with the current ratification, the Kampala amendments are far from being a declaratory instrument able to freeze the state of the law. Still, there might be implications in the long run. As Baxter points out again,

“the proof of a consistent pattern of conduct by non-parties becomes more difficult as the number of parties to the instrument increases. The number of the participants in the process of creating customary law may become so small that the evidence of their practice will be minimal or altogether lacking. Hence the paradox that as the number of the parties to a treaty increases, it becomes more difficult to demonstrate what is the state of customary international law.”[26]

Each subsequent application of customary international law, outside the framework provided in the treaty, instead of enforcing opinio juris, will remain controversial and be perceived as evidence of deviant practice and lawlessness.

[1] Donald M Ferencz, The Crime of Aggression: Some Personal Reflections on Kampala, 23 Leiden J. Int’l L. 906 (2010) (describing how Vattel, writing on sovereigns who take up arms without a lawful cause in his 1758 Law of Nations, states that they are “chargeable with all the evils, all the horrors of the war: all the effusion of blood, the desolation of families, the rapine, the acts of violence, the ravages, the conflagrations, are his works and his crimes. He is guilty of a crime against the enemy . . . he is guilty of a crime against his people . . . finally, he is guilty of a crime against mankind in general, whose peace he disturbs, and to whom he sets a pernicious example.”)

[2] General Treaty for Renunciation of War as an Instrument of National Policy art. I, Aug. 27, 1928, 46 Stat. 2343, 94 L.N.T.S. 57.

[3] Agreement for the Prosecution and Punishment of the Major War Criminals of the European Axis, Annex art. VI(a), Aug. 8, 1945, 59 Stat. 1544, 1547, 82 U.N.T.S. 279, 288.

[4] See George A Finch, The Nuremberg Trial and International Law, The, 41 Am. J. Int’l L. (1947).

[5] U.N. Charter art. 2, para. 4 (“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.”).

[6] Id. art. 51 (“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…”).

[7] Id. art. 42 (“Should the Security Council consider that measures provided for in Article 41 would be inadequate or have proved to be inadequate, it may take such action by air, sea, or land forces as may be necessary to maintain or restore international peace and security. Such action may include demonstrations, blockade, and other operations by air, sea, or land forces of Members of the United Nations.”).

[8] G.A. Res. 3314 (XXIX), Annex, U.N. Doc. A/RES/3314 (Dec. 14, 1974).

[9] Id. art.3.

[10] Id. art.4.

[11] See Military and Paramilitary Activities in and against Nicaragua (Nicar. v. U.S.), Judgment, 1986 I.C.J. 14; Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 I.C.J. 226; Armed Activities on the Territory of the Congo (Dem. Rep. Congo v. Uganda), Judgment, 2005 I.C.J. 168.

[12] See e.g Antonio Cassese, International Law 310 (2005); W Michael Reisman, Assessing Claims to Revise the Laws of War, 97 Am. J. Int’l L. (2003); S.C. NEFF, War and the Law of Nations: A General History (2005).

[13] Review Conference of the Rome Statute of the International Criminal Court, Kampala, Uganda, May 31-June 11, 2010, The Crime of Aggression, Article 8bis para 2, RC/Res.6, Annex I (June 11, 2010) (“Any  of the following acts, regardless of a declaration of war, shall, in accordance with United Nations General Assembly resolution 3314 (XXIX) of 14 December 1974, qualify as an act of aggression:

(a) The invasion or attack by the armed forces of a State of the territory of another State, or any military occupation, however temporary, resulting from such invasion or attack, or any annexation by the use of force of the territory of another State or part thereof;

(b) Bombardment by the armed forces of a State against the territory of another State or the use of any weapons by a State against the territory of another State;

(c) The blockade of the ports or coasts of a State by the armed forces of another State;

(d) An attack by the armed forces of a State on the land, sea or air forces, or marine and air fleets of another State;

(e) The use of armed forces of one State which are within the territory of another State with the agreement of the receiving State, in contravention of the conditions provided for in the agreement or any extension of their presence in such territory beyond the termination of the agreement;

(f) The action of a State in allowing its territory, which it has placed at the disposal of another State, to be used by that other State for perpetrating an act of aggression against a third State;

(g) The 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 the acts listed above, or its substantial involvement therein.”).

[14] See Richard Baxter, Treaties and Custom, in 129 Recueil des Cours de l’Academie de Droit International 97, (1970).


[16] Rep. of the Int’l Law Comm’n, 48th Sess., U.N. Doc. A/51/10; GAOR, 51st Sess., Supp. No. 10, at 9 (1996).

[17] See Harold H. Koh, International Law in Cyberspace, 54 Harv. Int’l L. J. Online 1, 1 (2012),

[18] Carolyn Duffy Marsan, How close is World War 3.0, NETWORK WORLD (Aug. 22, 2007),; Jonathan Richards, Thousands of Cyber Attacks Each Day on Key Utilities, TIMES (U.K.) (Aug. 23, 2008),

[19] U.S., International Strategy for Cyberspace: Prosperity, Security, and Openness in a Networked World (May 2011),

[20] See Jonathan A. Ophardt, Cyber Warfare and the Crime of Aggression: The Need for Individual Accountability on Tomorrow’s Battlefield, Duke. L. & Tech. Rev. (2010) (citing Technology Quarterly-Cyber Warfare: Marching Off to Cyberwar, THE ECONOMIST, (Dec. 6, 2008)).

[21] John F. Murphy, Computer Network Attacks by Terrorists: Some Legal Dimensions, in 76 Int’l Law Studies: Computer Network Attack and International 323 (Michael N. Schmitt & Brian T. O’Donnell eds., 2002).

[22] W. Michael Reisman, Reflections on the Judicialization of the Crime of Aggression, 39 Yale. J. Int’l L. Online 66, 69 (2014). See also Tai-Heng Cheng, Making International Law Without Agreeing What It Is, 10 Wash. U. Global Stud. L. Rev. (2011).

[23] Reisman, supra note 22, at 70.

[24] See Armed Activities on the Territory of the Congo (Dem. Rep. Congo v. Uganda), Judgment, 2005 I.C.J. 168.

[25] See Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, 2004 I.C.J. 136.

[26] Baxter, supra note 14, at 64.

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