A/HRC/40/49 that can help to mitigate or reduce children’s vulnerability. Considering a lack of accountability for child abduction, particularly in terms of investigation, arrests and prosecution by national authorities, there is also a need to provide guidance to practitioners for possible advocacy and policy initiatives in that regard. The Office of the Special Representative is thus working on developing a guidance note for practitioners in the field on monitoring, ending, preventing and responding to child abduction in situations of armed conflict. It is expected that it will be published in 2019 and will also shine a light on the protection challenges posed by cross-border abduction and the measures that can be taken at subregional levels to respond to and prevent them. B. Children of or recruited as foreign fighters 13. The recruitment and use of children by parties to conflict is not a new phenomenon and non-State armed groups using violent extremist tactics are by no means the only ones committing such violations. However, child recruitment and use by those groups raises new challenges from a child protection perspective and the situation is compounded by the transnational nature of violent extremism, which has favoured the emergence of transnational recruitment and the involvement of children in the phenomenon of foreign fighters. 14. It is estimated that since 2011, between 30,000 and 42,000 foreign fighters from some 120 countries have travelled to Iraq and the Syrian Arab Republic to join groups affiliated to ISIL or Al-Qaida. By November 2017, nearly 7,000 foreign fighters were believed to have died on the battlefield and at least 14,910 were reported to have left conflict zones, with some 6,800 returning to their home countries. Those numbers include a significant proportion of children. Given the expanding reach and propaganda of such groups, child recruitment and use have not been limited to conflict-ridden areas. Increasing numbers of children crossed borders either on their own or with their families to areas controlled by groups using extreme violence. Children were also abducted by those groups and forced to cross borders during their association. Data collected between 2015 and 2016 in the framework of the United Nations Office on Drugs and Crime (UNODC) Handbook on Children Recruited and Exploited by Terrorist and Violent Extremist Groups: the Role of the Justice System showed that among 89 children who died in hostilities were nationals not only of Iraq and the Syrian Arab Republic, but also of Australia, France, Lebanon, Libya, Morocco, Nigeria, Saudi Arabia, the Sudan, Tajikistan, Tunisia, the United Kingdom of Great Britain and Northern Ireland and Yemen. Those figures did not include children taken to ISIL territory by their families. 15. Children of or recruited as foreign fighters are not only victims of use, killing, maiming, enslavement, sexual exploitation, constant fear, indoctrination and psychological pressure, but also witnesses to and/or alleged perpetrators of violations. Violence has a severe impact on the physical and mental well-being of those children. That is not limited to children in areas of conflict, it also applies to children returning from those areas, whether they travelled on their own or were taken there by adults, either voluntarily or not. 16. Governments faced with armed groups whose strategies include inflicting maximum suffering on civilians may be tempted to apply different legal standards from those applying to such acts. Particularly in contexts where Governments are engaged in operations to counter violent extremism, it is more important than ever to ensure they are carried out in full compliance with international humanitarian, human rights and refugee law. Failure to abide by those obligations only worsens the suffering of the civilian population and can have the unintended consequence of creating or adding to real or perceived grievances in the affected population. Moreover, when responding to extreme violence, Member States should ensure that their rules of engagement take into account the fact that a large number of children are associated with such groups and may have been placed on the front line, either to engage in combat or as human shields. 17. The Special Representative continues to remind Member States that all children associated with parties to conflict and encountered in security operations should be treated primarily as victims rather than as security threats. Children who have been abducted, 6