C. Paulussen nationality, a measure more and more used by states in the counterterrorism and national security context, including against alleged foreign (terrorist) fighters. This article will briefly present a number of international human rights law considerations related to the topic of citizenship stripping of foreign fighters before focusing on considerations in the context of international humanitarian law. These are obviously the most interesting for the readers of the International Review of the Red Cross and, moreover, they have been less frequently the subject of academic debate. In the final part of this article, a number of conclusions will be offered. Before starting though, the relevance of this contribution in this special issue on “Counterterrorism and sanctions” must first be clarified. Indeed, should citizenship stripping or deprivation of nationality (the two terms will be used interchangeably here) be seen as a sanction in the first place? This contribution argues that it should. Although the word “sanction” is often linked to punishment, an objective sometimes lacking in the context of citizenship stripping,9 its scope is in fact broader. According to Black’s Law Dictionary, a sanction is defined as, among other things, “[a] penalty or coercive measure that results from failure to comply with a law, rule, or order”.10 Deprivation of nationality in any case fits the second part of this definition. But even if we were to view a sanction to be limited to a penalty, and even if some governments present citizenship stripping as a non-punitive measure meant to protect national security, the connection to crime and punishment is in fact made at other times. Sandra Mantu has, for example, noted that “we are actually witnessing a new way of conceptualising state power whereby depriving individuals of their citizenship status is a form of penal sanction to be applied to citizens in response to perceived crimes against public security by act or by association [original footnote omitted]”.11 Hence, in all cases, it can be argued that citizenship stripping constitutes a (de facto) sanction, even if we were to follow a definition limited to measures of a punitive nature, and thus fits this special issue. 9 For example, when the Dutch Government, in December 2014, proposed a new bill on the amendment of the Netherlands Nationality Act, to allow the Government to withdraw Dutch citizenship, without a criminal conviction, when the person in question had joined an organization which is taking part in a national or international armed conflict and which has been placed by the Minister of Security and Justice on a list of organizations that constitute a threat to national security, the Minister clarified that the objective of this measure is the protection of national security, which should be distinguished from the objective of using criminal law. See C. Paulussen, “Repressing the Foreign Fighters Phenomenon and Terrorism in Western Europe: Towards an Effective Response Based on Human Rights”, ICCT Research Paper, November 2016, available at: https://icct.nl/app/uploads/2016/11/ICCT-PaulussenRule-of-Law-Nov2016-1.pdf, p. 16. See also, more generally, M. Tripkovic, “Transcending the Boundaries of Punishment: On the Nature of Citizenship Deprivation”, British Journal of Criminology, 23 February 2021, available at: https://academic.oup.com/bjc/advance-article-abstract/doi/10.1093/bjc/ azaa085/6146956, abstract: “Departing from a dominant perspective that considers denationalization as punishment, this article conducts an original study of citizenship policies in 37 European democracies and contrasts them with key principles of punishment. The findings raise serious doubts regarding the penal nature of denationalization: I propose instead that denationalization is better understood as a sui generis sanction, which seeks to relieve the polity of those members who fail to satisfy fundamental citizenship requirements.” 10 B. A. Garner, Black’s Law Dictionary, 8th ed., Thomson West, St. Paul, MN, 2004, p. 1368. 11 S. Mantu, “Citizenship in Times of Terror: Citizenship Deprivation in the UK”, Nijmegen Migration Law Working Papers Series, 2015/02, available at: https://repository.ubn.ru.nl/handle/2066/143370, p. 5. 608