such travel.46 It also requires states to prevent entry to their territory or transit of FTFs47 and calls upon them to co-operate, for example, in preventing radicalization to terrorism, and developing and implementing prosecution, rehabilitation and reintegration strategies for returning FTFs.48 Furthermore, it calls on states to take a number of additional measures to enhance international co-operation, including in sharing information to identify FTFs and countering violent extremism in order to prevent terrorism.49 Resolution 2178 (2014) also demands that “all foreign terrorist fighters disarm and cease all terrorist acts and participation in an armed conflict.”50 The former UN Special Rapporteur on counter-terrorism observed in strikingly critical terms that UNSC Resolution 2178 (2014) “imposes upon all Member States far-reaching new legal obligations without any effort to define or limit the categories of persons who may be identified as ‘terrorists’ by an individual state,” and that “[t]his approach carries a huge risk of abuse, as various states apply notoriously wide, vague or abusive definitions of terrorism, often with a clear political or oppressive motivation.”51 The lack of a definition of terrorism in UNSC resolutions or international law more broadly, has been well recognized, while associated concerns are greatly intensified in the context of the added layers of ambiguity around each of the elements of the phrase “foreign terrorist fighters”, as discussed further in section 3.1, below. UNSC Resolution 2396 (2017) has been described as going significantly further than its predecessor in several respects. It requires states to “strengthen their efforts in border security, information-sharing, and criminal justice in ways that have serious implications for domestic legal regimes”, for human rights and the rule of law.52 In particular, its call to member states to develop “watch lists or databases” of persons suspected of engagement in or support for FTFs, and to share a broad range of relevant information, including personal biometric data with other states, necessitates careful attention as to whether and how human rights are being protected in co-operating states.53 Echoing commentary on its predecessor, Resolution 2396 (2017), has been criticized for its 46  Ibid., para. 6. 47  Ibid., para. 8. 48  Ibid., para. 4. 49  Ibid., paras. 11-14 and 15-19, respectively. 50  Ibid., para. 1. 51  M. Scheinin (former UN Special Rapporteur on counter-terrorism), “Back to post-9/11 panic? Security Council resolution on foreign terrorist fighters”, Just Security, 23 September 2014, <www.justsecurity. org/15407/post-911-panic-security-council-resolution-foreign-terrorist-fighters-scheinin/> (hereafter, M. Scheinin, “Back to post-9/11”). See also: M. Scheinin, “A Comment on Security Council Res 2178 (Foreign Terrorist Fighters) as a ‘Form’ of Global Governance”, Just Security, 6 October 2014, <www.justsecurity. org/15989/comment-security-council-res-2178-foreign-fighters-form-global-governance>. 52  F. Ní Aoláin, (current UN Special Rapporteur on counter-terrorism), “The UN Security Council, Global Watch Lists, Biometrics and the threat to the rule of law”, Just Security, 17 January 2018, <www.justsecurity. org/51075/security-council-global-watch-lists-biometrics/>, (hereafter, F. Ní Aoláin, “The UN Security Council, Global Watch Lists, Biometrics and the threat to the rule of law”). 53  Ibid., Ní Aoláin notes that “the principle of sharing assumes that all states value privacy equally; do not misuse information to target individuals outside of the rule of law; and that information practices including integrity, anonymity, destruction as appropriate are rule of law based…. [which is] not the case in practice.” Guidelines for Addressing the Threats and Challenges of “Foreign Terrorist Fighters” 17