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Published online by Cambridge University Press: 08 July 2020
Armed reprisals are the limited use of military force in response to unlawful actions perpetrated against states. Historically, reprisals provided a military remedy for states that had been wronged (often violently) by another state without having to resort to all-out war in order to counter or deter such wrongful actions. While reprisals are broadly believed to have been outlawed by the UN Charter, states continue to routinely undertake such self-help measures. As part of the roundtable, “The Ethics of Limited Strikes,” this essay examines the doctrine of armed reprisals in light of recent instances of states using force “short of war” in this manner. We argue that the ban on reprisals has been largely ignored by states, and that recent attempts to apply the laws of armed conflict to the cyber domain (such as the Tallinn Manual) are further weakening this prohibition. We conclude that this is a potentially dangerous development that lowers the bar for resorting to military force, risking escalation and thereby further destabilizing the international system.
1 SeeKelsen, Hans, Principles of International Law (Clark, N.J.: Lawbook Exchange, 2003), p. 23Google Scholar.
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3 This then spurred a number of tit-for-tat retaliations between India and Pakistan. See “Balakot: Indian Air Strikes Target Militants in Pakistan,” BBC News, February 26, 2019, www.bbc.com/news/world-asia-47366718.
4 “UN Chief Urges India and Pakistan to Dial Down Tensions in Wake of Kashmir Attack,” UN News, February 20, 2019, news.un.org/en/story/2019/02/1033151.
5 Schmitt, Michael N., ed., Tallinn Manual 2.0 on the International Law Applicable to Cyber Operations, 2nd ed. (Cambridge, U.K.: Cambridge University Press, 2017), p. 330CrossRefGoogle Scholar.
6 Israel Defense Forces, “CLEARED FOR RELEASE: We thwarted an attempted Hamas cyber offensive against Israeli targets. Following our successful cyber defensive operation, we targeted a building . . . ,” Twitter, May 5, 2019, twitter.com/IDF/status/1125066395010699264.
7 Michael D. Shear, Eric Schmitt, Michael Crowley, and Maggie Haberman, “Strikes on Iran Approved by Trump, Then Abruptly Pulled Back,” New York Times, June 20, 2019; and Julian E. Barnes and Thomas Gibbons-Neff, “U.S. Carried Out Cyberattacks on Iran,” New York Times, June 22, 2019, www.nytimes.com/2019/06/22/us/politics/us-iran-cyber-attacks.html.
8 “Statement by the Department of Defense,” Defense.gov, January 2, 2020, www.defense.gov/Newsroom/Releases/Release/Article/2049534/statement-by-the-department-of-defense/source/GovDelivery/; Michael Crowley, Falih Hassan, and Eric Schmitt, “U.S. Strike in Iraq Kills Qassim Suleimani, Commander of Iranian Forces,” New York Times, January 2, 2020, www.nytimes.com/2020/01/02/world/middleeast/qassem-soleimani-iraq-iran-attack.html; and Stefan Talmon and Miriam Heipertz, “The U.S. Killing of Iranian General Qasem Soleimani: Of Wrong Trees and Red Herrings, and Why the Killing May Be Lawful after All” (Bonn Research Papers on Public International Law 18/2020, University of Bonn, Institute for Public International Law, February 2, 2020), p. 16.
9 “World Reacts to US Killing of Iran's Qassem Soleimani in Iraq,” Al Jazeera, January 3, 2020. See also Kate Holton, “UK Says U.S. Is Entitled to Defend Itself Following Iraq Attack,” Reuters, January 4, 2020, www.reuters.com/article/us-iraq-security-britain-wallace/uk-says-us-is-entitled-to-defend-itself-following-iraq-attack-idUSKBN1Z30M9.
10 Salpeter, Alan N. and Waller, Jonathan C., “Armed Reprisals during Intermediacy—A New Framework for Analysis in International Law,” Villanova Law Review 17, no. 2 (1971), p. 274Google Scholar.
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12 See Taulbee, James Larry and Anderson, John, “Reprisal Redux,” Case Western Reserve Journal of International Law 16, no. 3 (1984), pp. 312–13Google Scholar.
13 For example, the Special Committee of Jurists, established by the League of Nations to examine the 1923 Corfu incident, concluded that reprisals “may or may not be” consistent with the Covenant of the League of Nations. The Permanent Court of International Justice also characterized reprisals as an “alleged right” in 1931, while the Institute of International Law passed a resolution indicating that armed reprisals were restricted similarly to all recourse to war—restricted but not entirely banned. See Darcy, Shane, “Retaliation and Reprisal,” in Weller, Marc, ed., Oxford Handbook on the Use of Force (Oxford: Oxford University Press, 2013), pp. 9–10Google Scholar.
14 O'Connell, “Popular but Unlawful Armed Reprisal,” p. 327; and Darcy, “Retaliation and Reprisal,” p. 879.
15 See, especially, Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United States of America), 1986 I.C.J. 14, paras. 191, 195.
16 See United Nations General Assembly, preamble to Article 50(1)(a); “Declaration on Principles of International Law concerning Friendly Relations and Co-Operation among States in Accordance with the Charter of the United Nartions,” A/RES/2625 (XXV), October 24, 1970; Brierly, J. L., The Law of Nations: An Introduction to the International Law of Peace (New York: Oxford University Press, 1963), p. 415Google Scholar; and International Court of Justice, advisory opinion, “Legality of the Threat or Use of Nuclear Weapons” (July 8, 1996), para. 46.
17 Bowett, Derek, “Reprisals involving Recourse to Armed Force,” American Journal of International Law 66, no. 1 (January 1972), p. 10CrossRefGoogle Scholar. See also Tucker, Robert W., “Reprisals and Self-Defense: The Customary Law,” American Journal of International Law 66, no. 3 (July 1972), pp. 586–96CrossRefGoogle Scholar.
18 Bowett, “Reprisals involving Recourse to Armed Force,” p. 11.
19 Taulbee and Anderson, “Reprisal Redux,” pp. 309–10; and Tucker, “Reprisals and Self-Defense,” p. 587.
20 Article 43, Charter of the United Nations, October 24, 1945.
21 Nicar. v. U.S., para. 249.
22 Ibid., para. 211.
23 Ruys, Tom, ‘Armed Attack’ and Article 51 of the UN Charter Evolutions in Customary Law and Practice (Cambridge, U.K.: Cambridge University Press, 2010), p. 141Google Scholar.
24 Oil Platforms (Islamic Republic of Iran v. United States of America), 2003 I.C.J. 90, separate opinion of Judge Simma, para. 13: “But we may also encounter a lower level of hostile military action, not reaching the threshold of an ‘armed attack’ within the meaning of Article 51 of the UN Charter. Against such hostile acts, a State may, of course, defend itself, but only within the more limited range and quality of responses (the main difference being that possibility of collective self-defense does not arise, cf. Nicaragua) and bound to necessity, proportionality, and immediacy in time in a particular way.”
25 Oil Platforms, para. 12.
26 The requirement for greater clarity regarding how international law applies to cyber operations became particularly pertinent after the Russian-supported cyberattacks against the Estonian government on April 27, 2007. See Toomas Hendrik Ilves, forward in Schmitt, Tallinn Manual 2.0, pp. xxiii–xxiv.
27 Schmitt, Michael N., ed., Tallinn Manual on the International Law Applicable to Cyber Warfare (Cambridge, U.K.: Cambridge University Press, 2013)Google Scholar; and Schmitt, Tallinn Manual 2.0.
28 Schmitt, Tallinn Manual 2.0, n.14, pp. 2–3.
29 See, for instance, Gross, Michael L. and Meisels, Tamar, Soft War: The Ethics of Unarmed Conflict (Cambridge, U.K.: Cambridge University Press, 2017)Google Scholar; Lucas, George, Ethics and Cyber Warfare: The Quest for Responsible Security in the Age of Digital Warfare (Oxford University Press, 2017)CrossRefGoogle Scholar; and Finnemore, Martha, “Ethical Dilemmas in Cyberspace,” Ethics & International Affairs 32, no. 4 (Winter 2018), pp. 457–62CrossRefGoogle Scholar.
30 For a list of experts and contributors to the first Tallinn Manual, see Schmitt, Tallinn Manual on the International Law Applicable to Cyber Warfare, pp. xix–xxii; for experts and contributors to the second Tallinn Manual, see Schmitt, Tallinn Manual 2.0, pp. xii–xviii. See also Eric Talbot Jensen, “The Tallinn Manual 2.0: Highlights and Insights,” Georgetown Journal of International Law 48, p. 738.
31 Schmitt, Tallinn Manual 2.0, p. 328.
32 International Court of Justice, “Legality of the Threat or Use of Nuclear Weapons,” para. 39. See also Schmitt, Tallinn Manual 2.0, p. 328.
33 Schmitt, Tallinn Manual 2.0, p. 328.
34 Ibid., p. 125.
35 In the Tallinn Manuals, “injured state” refers to the state affected by the initial unlawful use of force. See, for instance, Schmitt, Tallinn Manual, p. 37, and Schmitt, Tallinn Manual 2.0, p. 125.
36 See Dinstein, Yoram, War, Aggression and Self-Defence, 4th ed. (Cambridge, U.K.: Cambridge University Press, 2005), p. 182Google Scholar.
37 O'Connell, “Popular but Unlawful Armed Reprisal,” p. 340.
38 See International Law Commission, Art. 50(1)(a), “Draft Articles on Responsibility of States for Internationally Wrongful Acts,” A/RES/56/83, November 2001, and Nicar. v. U.S., para. 249.
39 Schmitt, Tallinn Manual 2.0, p. 125.
40 These countermeasures include, for instance, proportionality, discrimination, and human rights law. See Schmitt, Tallinn Manual 2.0, pp. 125–26.
41 Ibid., p. 126.
42 Ibid., p. 125.
43 Israel Defense Forces, “CLEARED FOR RELEASE.”
44 In addition to countermeasures, states are also permitted to engage in acts of retorsion—that is, unfriendly or discourteous acts that are nonetheless lawful. See Darcy, “Retaliation and Reprisal,” p. 881.
45 Donald Trump, quoted in “US-Iran: Trump Says Military Was ‘Cocked and Loaded’ to Retaliate,” BBC News, June 21, 2019, www.bbc.com/news/world-us-canada-48714414.
46 Julian E. Barnes, “U.S. Cyberattack Hurt Iran's Ability to Target Oil Tankers, Officials Say,” New York Times, August 28, 2019, www.nytimes.com/2019/08/28/us/politics/us-iran-cyber-attack.html. See also Barnes and Gibbons-Neff, “US Carried Out Cyberattacks on Iran”; and Schmitt, Tallinn Manual 2.0, pp. 330–31.
47 Darcy, “Retaliation and Reprisal,” p. 895.
48 Brunstetter, Daniel R., “Wading Knee-Deep Into the Rubicon: Escalation and the Morality of Limited Strikes,” Ethics & International Affairs 34, no. 2 (July, 2020), pp. 161–173CrossRefGoogle Scholar. Pearlman, Wendy, “Syrian Views on Obama's Red Line: The Ethical Case for Strikes against Assad,” Ethics & International Affairs 34, no. 2 (July, 2020), pp. 189–200CrossRefGoogle Scholar.
49 On the principle of “probability of escalation,” see Brunstetter, Daniel R. and Braun, Megan, “From Jus ad Bellum to Jus ad Vim: Recalibrating Our Understanding of the Moral Use of Force,” Ethics & International Affairs 27, no. 1 (February 2013), pp. 98–100CrossRefGoogle Scholar.
50 Robert Jervis, “On the Current Confrontation with Iran,” War on the Rocks, January 9, 2020, warontherocks.com/2020/01/on-the-current-confrontation-with-iran/.
51 Ibid. See also Rowe, Neil C., “The Ethics of Cyberweapons in Warfare,” International Journal of Technoethics 1, no. 1 (January/March 2010), pp. 20–31Google Scholar.
52 Heinze, Eric A., “The Evolution of International Law in Light of the ‘Global War on Terror,’” Review of International Studies 37, no. 3 (July 2011), pp. 1083–84CrossRefGoogle Scholar.
53 See Deeks, Ashley, “‘Unwilling or Unable’: Toward a Normative Framework for Extra-Territorial Self-Defense,” Virginia Journal of International Law 52, no. 3 (2012), pp. 483–550Google Scholar.
54 Scharf, Michael P., “How the War against ISIS Changed International Law,” Case Western Reserve Journal of International Law 48, no. 1 (2016), pp. 50–51Google Scholar.
55 Ibid., p. 19.
