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Sovereignty is a core principle of international law. According to a widely accepted definition of the term in the 1928 Island of Palmas arbitral award,
[s]overeignty in the relations between States signifies independence. Independence in regard to a portion of the globe is the right to exercise therein, to the exclusion of any other State, the functions of a State.[1]
Multiple declarations by the UN,[2] NATO,[3] OSCE,[4] the European Union,[5] and individual States have confirmed that international law applies in cyberspace. Accordingly, so too does the principle of sovereignty. However, there is some debate as to whether this principle operates as a standalone rule of international law, the breach of which gives rise to state responsibility.
  • For the proponents of this view, the prohibition on violating the sovereignty of other States is a substantive primary rule of international law, the breach of which is an internationally wrongful act. This view was unanimously accepted by the experts who prepared the Tallinn Manual 2.0.[6] It has also been adopted by several States including Austria,[7] the Czech Republic,[8] Finland,[9] France,[10] Germany,[11] Iran,[12] and the Netherlands.[13]
  • By contrast, the opposing view is that sovereignty is a principle of international law that may guide State interactions, but it does not amount to a standalone primary rule.[14] This view has now been adopted by one State, the United Kingdom,[15] and has been endorsed by the U.S. Department of Defense General Counsel.[16] By this approach, cyber operations cannot violate sovereignty as a rule of international law, although they may constitute prohibited intervention, use of force, or other internationally wrongful acts.

The remainder of this section proceeds on the basis of the former “sovereignty-as-rule” approach. Those espousing the latter “sovereignty-as-principle” approach should refer to other relevant sections of the legal analysis (such as that on the prohibition of intervention).

It is understood that sovereignty has both an internal and an external component.[17] In the cyber context, the “internal” facet of sovereignty entails that “[a] State enjoys sovereign authority with regard to the cyber infrastructure, persons, and cyber activities located within its territory, subject to its international legal obligations.”[18][19]

As a general rule, each State must respect the sovereignty of other States.[20] It is clear that a cyber operation with severe destructive effects, comparable to a “non-cyber” armed attack or a use of force against a State, constitutes a violation of its sovereignty; however, with more subtle cyber operations, the question is far from settled.[21]

The following modalities, highlighted in the Tallinn Manual 2.0, represent different ways of determining what a “sovereignty violation” might mean in the context of cyber operations:

  1. A State organ conducting cyber operations against a target State or entities or persons located there while physically present in the target State's territory violates the target State's sovereignty.[22] This was agreed by all Experts drafting the Manual; however, “a few” of the Experts thought that the extensive State practice carved out an exception for espionage operations.[23]
  2. Causation of physical damage or injury by remote means;[24] again, “a few” Experts took the position that this is a relevant but not a determinative factor by itself.[25]
  3. Causation of a loss of functionality of cyber infrastructure: although the Tallinn Manual 2.0 experts agreed that a loss of functionality constituted “damage” and thus a breach of sovereignty, no consensus could be achieved as on the precise threshold for a loss of functionality (the necessity of reinstallation of operating system or other software was proposed but not universally accepted);[26] Below this threshold, there was no agreement among the Experts whether operations that do not cause physical consequences or a loss of functionality qualify as a violation of sovereignty.[27]
  4. Interference with data or services that are necessary for the exercise of "inherently governmental functions";[28] although the Experts could not conclusively define the term "inherently governmental functions", they agreed that, for example, the conduct of elections would so qualify.[29]
  5. Usurpation of "inherently governmental functions", such as exercise of law enforcement functions in another State’s territory without justification.[30]

The Tallinn Manual’s view of what constitutes a violation of sovereignty has been expressly endorsed by several States including Germany[31] and the Netherlands.[32] An alternative test has been proposed by France, which argues that a breach of sovereignty occurs already when there is “any unauthorised penetration by a State of [the victim State’s] systems”.[33]

Attributing the relevant cyber operation to a State different from the target State is a necessary prerequisite for qualifying the cyber operation as a violation of the target State's sovereignty.

Whether non-State actors can violate territorial sovereignty on their own is a matter of disagreement.[34]

National positions


The Czech Republic








New Zealand


The Netherlands

National position of the Nertherlands

United Kingdom

"[..]a further contested area amongst those engaged in the application of international law to cyber space is the regulation of activities that fall below the threshold of a prohibited intervention, but nonetheless may be perceived as affecting the territorial sovereignty of another state without that state’s prior consent. Some have sought to argue for the existence of a cyber specific rule of a “violation of territorial sovereignty” in relation to interference in the computer networks of another state without its consent. Sovereignty is of course fundamental to the international rules-based system. But I am not persuaded that we can currently extrapolate from that general principle a specific rule or additional prohibition for cyber activity beyond that of a prohibited intervention. The UK Government’s position is therefore that there is no such rule as a matter of current international law.[35]

United Kingdom: 2021

"Sovereignty, as a general principle, is a fundamental concept in international law. The United Kingdom recalls that any prohibition on the activities of States whether in relation to cyberspace or other matters, must be clearly established either in customary international law or in a treaty binding upon the States concerned. The United Kingdom does not consider that the general concept of sovereignty by itself provides a sufficient or clear basis for extrapolating a specific rule or additional prohibition for cyber conduct going beyond that of non-intervention referred to above. At the same time, the United Kingdom notes that differing viewpoints on such issues should not prevent States from assessing whether particular situations amount to internationally wrongful acts and arriving at common conclusions on such matters."[36]

United States of America: 2012

"States conducting activities in cyberspace must take into account the sovereignty of other states, including outside the context of armed conflict. The physical infrastructure that supports the Internet and cyber activities is generally located in sovereign territory and subject to the jurisdiction of the territorial state. Because of the interconnected, interoperable nature of cyberspace, operations targeting networked information infrastructures in one country may create effects in another country. Whenever a state contemplates conducting activities in cyberspace, the sovereignty of other states needs to be considered."[37]

United States of America: 2016

"[..] remote cyber operations involving computers or other networked devices located on another State’s territory do not constitute a per se violation of international law. In other words, there is no absolute prohibition on such operations as a matter of international law. This is perhaps most clear where such activities in another State’s territory have no effects or de minimis effects.

Most States, including the United States, engage in intelligence collection abroad. As President Obama said, the collection of intelligence overseas is “not unique to America.” As the President has also affirmed, the United States, like other nations, has gathered intelligence throughout its history to ensure that national security and foreign policy decisionmakers have access to timely, accurate, and insightful information. Indeed, the President issued a directive in 2014 to clarify the principles that would be followed by the United States in undertaking the collection of signals intelligence abroad.

Such widespread and perhaps nearly universal practice by States of intelligence collection abroad indicates that there is no per se prohibition on such activities under customary international law. I would caution, however, that because “intelligence collection” is not a defined term, the absence of a per se prohibition on these activities does not settle the question of whether a specific intelligence collection activity might nonetheless violate a provision of international law.

Although certain activities—including cyber operations — may violate another State’s domestic law, that is a separate question from whether such activities violate international law. The United States is deeply respectful of other States’ sovereign authority to prescribe laws governing activities in their territory. Disrespecting another State’s domestic laws can have serious legal and foreign policy consequences. As a legal matter, such an action could result in the criminal prosecution and punishment of a State’s agents in the United States or abroad, for example, for offenses such as espionage or for violations of foreign analogs to provisions such as the U.S. Computer Fraud and Abuse Act. From a foreign policy perspective, one can look to the consequences that flow from disclosures related to such programs. But such domestic law and foreign policy issues do not resolve the independent question of whether the activity violates international law."[38]


See also

Notes and references

  1. Island of Palmas (Neth. v. U.S.), 2 RIAA 829, 838 (Perm. Ct. Arb. 1928).
  2. UNGA Res 71/237 (30 December 2015) UN Doc A/RES/20/237.
  3. North Atlantic Treaty Organization, 'Wales Summit Declaration' (issued by the Head of State and Government participating in the meeting of the North Atlantic Council in Wales (5 September 2015) para 72.
  4. Organization for Security and Cooperation in Europe, Decision No. 1202, OSCE Confidence-Building Measures to Reduce the Risks of Conflict Stemming from the Use of Information and Communication Technologies (Permanent Council, 10 March 2016) PC.DEC/1202.
  5. Council of the European Union,"Council Conclusions on the Joint Communication to the European Parliament and the Council: Resilience, Deterrence and Defence: Building strong cybersecurity for the EU" (Council conclusions, 20 November 2017).
  6. Michael N Schmitt, 'Virtual Disenfranchisement: Cyber Election Meddling in the Grey Zones of International Law' (2018) 19 ChiJIntlL 30,40; Tallinn Manual 2.0, commentary to rule 4, para 2 (‘States shoulder an obligation to respect the sovereignty of other States as a matter of international law’).
  7. Austria, Pre-Draft Report of the OEWG - ICT: Comments by Austria (31 March 2020), stating that ‘a violation of the principle of State sovereignty constitutes an internationally wrongful act – if attributable to a State – for which a target State may seek reparation under the law of State responsibility’.
  8. Czech Republic, Statement by Mr. Richard Kadlčák, Special Envoy for Cyberspace, 2nd substantive session of the Open-ended Working Group on developments in the field of information and telecommunications in the context of international security (11 February 2020), stating that ‘[t]he Czech Republic concurs with those considering the principle of sovereignty as an independent right and the respect to sovereignty as an independent obligation.’
  9. Finland, ‘International law and cyberspace: Finland’s national positions’ (15 October 2020), 3, stating that ‘Finland sees sovereignty as a primary rule of international law, a breach of which amounts to an internationally wrongful act and triggers State responsibility. This rule is fully applicable in cyberspace.’
  10. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, stating that ‘Any unauthorised penetration by a State of French systems or any production of effects on French territory via a digital vector may constitute, at the least, a breach of sovereignty’.
  11. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 3, noting that ‘Germany agrees with the view that cyber operations attributable to States which violate the sovereignty of another State are contrary to international law’.
  12. Iran, ‘Declaration of General Staff of the Armed Forces of the Islamic Republic of Iran Regarding International Law Applicable to the Cyberspace’ (July 2020), para 4 (‘Any utilization of cyberspace if and when involves unlawful intrusion to the (public or private) cyber structures which is under the control of another state, maybe constituted as the violation of the sovereignty of the targeted state.’).
  13. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), stating that ‘countries may not conduct cyber operations that violate the sovereignty of another country’.
  14. Gary P. Corn and Robert Taylor, ‘Sovereignty in the Age of Cyber’ (2017) 111 AJIL Unbound 207, 208 (arguing that sovereignty is ‘a principle of international law that guides state interactions’).
  15. Jeremy Wright, ‘Cyber and International Law in the 21st Century’ (23 May 2018) (stating that he was ‘not persuaded that we can currently extrapolate from that general principle a specific rule or additional prohibition for cyber activity beyond that of a prohibited intervention. The UK Government’s position is therefore that there is no such rule as a matter of current international law’); see also Memorandum from JM O’Connor, General Counsel of the Department of Defense, ‘International Law Framework for Employing Cyber Capabilities in Military Operations’ (19 January 2017) (considering that sovereignty is not ‘a binding legal norm, proscribing cyber actions by one State that result in effects occurring on the infrastructure located in another State, or that are manifest in another State’), as cited by Sean Watts & Theodore Richard, 'Baseline Territorial Sovereignty and Cyberspace' (2018) 22 Lewis & Clark L. Rev. 771, 829.
  16. Paul C. Ney, DOD General Counsel Remarks at U.S. Cyber Command Legal Conference, 2 March 2020, arguing that ‘the Department believes there is not sufficiently widespread and consistent State practice resulting from a sense of legal obligation to conclude that customary international law generally prohibits such non-consensual cyber operations in another State’s territory’.
  17. Cf. James Crawford, Brownlie's Principles of Public International Law (OUP 2012) 448.
  18. Tallinn Manual 2.0, rule 2.
  19. Sovereignty over cyber infrastructure derives from the traditional concept of sovereignty, independent of the use of cyberspace. See Wolff Heintschel von Heinegg, 'Territorial Sovereignty and Neutrality in Cyberspace' (2013) 89 Int’l L. Stud. 123 (noting that '[t]erritorial sovereignty [..] implies that, subject to applicable customary or conventional rules of international law, the State alone is entitled to exercise jurisdiction, especially by subjecting objects and persons within its territory to domestic legislation and to enforce these rules.')
  20. UN GA Res 2625 (XXV) (24 October 1970) (Friendly Relations Declaration), preamble (emphasizing “that the purposes of the United Nations can be implemented only if States enjoy sovereign equality and comply fully with the requirements of this principle in their international relations”); Tallinn Manual 2.0, rule 4.
  21. Tallinn Manual 2.0, commentary to rule 4, para 5 and 12.
  22. See, eg, Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v Nicaragua) and Construction of a Road in Costa Rica along the San Juan River (Nicaragua v Costa Rica) (Judgment) [2015] ICJ Rep 665, 704–05, paras 97–99 (holding that the presence of Nicaragua’s military personnel in the territory under Costa Rica’s sovereignty amounted to a violation of Costa Rica’s territorial sovereignty); see also Tallinn Manual 2.0, commentary to rule 4, para 6.
  23. Tallinn Manual 2.0, commentary to rule 4, para 7; commentary to rule 32, para 9.
  24. Tallinn Manual 2.0, commentary to rule 4, para 11.
  25. Tallinn Manual 2.0, commentary to rule 4, para 12.
  26. Tallinn Manual 2.0, commentary to rule 4, para 13.
  27. Tallinn Manual 2.0, commentary to rule 4, para 14.
  28. Tallinn Manual 2.0, commentary to rule 4, para 15.
  29. Tallinn Manual 2.0, commentary to rule 4, para 16.
  30. Tallinn Manual 2.0, commentary to rule 4, para 18.
  31. Germany, ‘On the Application of International Law in Cyberspace: Position Paper’ (March 2021), p. 4.
  32. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019), p. 3.
  33. French Ministry of the Armies, International Law Applied to Operations in Cyberspace, p. 6.
  34. In favour: see, eg, Theodore Christakis, ‘The ICJ Advisory Opinion on Kosovo: Has International Law Something to Say about Secession?’ (2011) 24 LJIL 73, 84; Marcelo Kohen, ‘The Court’s Contribution to Determining the Content of Fundamental Principles of International Law’ in Giorgio Gaja and Jenny Grote Stoutenburg (eds), Enhancing the Rule of Law through the International Court of Justice (Brill 2012) 145. Against: see, eg, Tallinn Manual 2.0, commentary to rule 4, para 3.
  35. Attorney General Jeremy Wright:Cyber and International Law in the 21st Century, 23 May 2018
  36. United Kingdom Foreign, Commonwealth & Development Office, Application of international law to states’ conduct in cyberspace: UK statement, 3 June 2021
  37. Harold Hongju Koh, International Law in Cyberspace, 18 September 2012, 6
  38. Brian J. Egan, International Law and Stability in Cyberspace, 10 November 2016 11-13.

Bibliography and further reading