Stripping foreign fighters of their citizenship: International human rights and humanitarian law considerations the least intrusive means possible and shall: (a) Be necessary in a democratic society to pursue a defined legitimate aim, as permitted by international law; and (b) Be proportionate to the benefit obtained in achieving the legitimate aim in question.24 As argued before,25 deprivation of nationality can never be seen as the least intrusive means available and be necessary and proportionate. After all, mono-citizens who may have been in the same situation, who may have committed similar crimes and who may pose a similar security risk will not be deprived of their nationality (to avoid statelessness) but will face other, less far-going measures, such as a temporary area ban. If mono-citizens can be responded to in a less intrusive way, then why can these responses not also be applied to dual citizens? This entails that it is extremely difficult to justify deprivation of nationality as the least intrusive and thus necessary and proportionate means towards a certain aim, hence making the measure arbitrary, and thus prohibited under international law. Moreover, as explained above, the measure may never violate peremptory or nonderogable norms of international law, nor impair the essence of any human right, such as the principles of non-discrimination and equality.26 In this respect, serious problems under international law arise as well, for the measure can and will only be applied to dual citizens. This clearly creates two different classes of citizens. Indeed, in an amicus curiae brief submitted to the Dutch Immigration and Naturalisation Service, the UN Special Rapporteur on contemporary forms of racism, racial discrimination, xenophobia and related intolerance E. Tendayi Achiume likewise concluded: The Netherlands’ policy to subject Dutch citizens to differential treatment on the basis of their mono or dual citizenship is inconsistent with its international human rights law [obligations]. The Netherlands’ policy to use individuals’ status as Dutch mono or dual nationals to determine eligibility for citizenship revocation results in discriminatory tiers of citizenship: full citizenship for Dutch mono nationals and less-secure citizenship for Dutch dual nationals. Because this result contradicts its international human rights law obligations to guarantee equality before the law and equal protection of the law to all of its citizens, the Netherlands must not rely on any mono-/dual-nationality distinction in determining permissibility of citizenship revocation.27 This brief part has demonstrated that deprivation of nationality is highly problematic under international human rights law. But the measure is also 24 Human Rights Council, above note 22, para. 16. 25 C. Paulussen, above note 12, p. 226. 26 See also Institute on Statelessness and Inclusion, above note 16, p. 10: “[a] State must not deprive any person or group of persons of their nationality as a result of direct or indirect discrimination in law or practice, on any ground prohibited under international law, including race, colour, sex, language, religion, political or other opinion, national or social origin, ethnicity, property, birth or inheritance, disability, sexual orientation or gender identity, or other real or perceived status, characteristic or affiliation.” 27 Office of the United Nations High Commissioner for Human Rights, above note 15, para. 36. 611