A/74/136 82. With respect to migration-related detention of children, research for the study and questionnaire responses reveal that at least 21 States do not, or claim not to, deprive children of their liberty for migration-related purposes. 83. The Guidelines for the Alternative Care of Children of 2009 seem to have had an impact on the deinstitutionalization practices of States. While in the global study on violence against children of 2006, the total number of children in institutions was given as 8 million, research conducted for the current study estimate the number to be between 3.5 and 5.5 million. Deinstitutionalization measures have been adopted, for example, in Central and Eastern Europe, as well as in Central Asia. Many of those children, including those with disabilities, have now been reunited with their families or placed in family-type settings in the community. 84. In the context of armed conflict, the Security Council, in resolution 2427 (2018), called on all parties to such conflicts to cease unlawful or arbitrary detention and encouraged States to establish “standard operating procedures for the rapid handover of the children concerned to relevant civilian child protection act ors”. This has already had a positive impact on State practice, as some African States have signed such handover protocols with the United Nations, transferring children associated with armed forces and armed groups to child welfare centres, with the aim o f ensuring their rehabilitation and reintegration into society. 85. With respect to national security, several States have opted for children associated with non-State armed groups designated as terrorist to be tried in special courts for children. While many States have been reluctant to bring home child nationals associated with such groups from conflict-affected areas, some States have adopted return plans with clear responsibilities for State authorities concerning the necessary steps for the safety, reintegration and rehabilitation of such children. VII. Conclusions A. Magnitude of the phenomenon 86. Data collected for the study and well-grounded scientific approximations indicate that, altogether, a minimum of between 1.3 and 1.5 million chil dren are deprived of liberty per year. Of those, the largest number are in institutions (430,000–680,000), followed by those in the administration of justice (410,000), migration-related detention (330,000), in armed conflict situations (35,000) and for national security reasons (1,500). An additional 19,000 children are living with their primary caregivers in prisons. The Independent Expert wishes to stress that those figures are arrived at on the basis of scientifically sound methodologies, yet remain highly conservative owing to the scarcity of official and reliable disaggregated data. In particular, the figures do not include the approximately 1 million children in police custody and an even higher number of children deprived of liberty de facto in institutions. 87. The majority of States which responded to the questionnaire had difficulties in providing comprehensive, up-to-date and disaggregated data on the number of children in various situations of detention. Administrative records are particularly limited in the context of migration, institutions, national security and armed conflict. 16/23 19-11838