Terrorism constitutes one of the most serious threats to international peace and security. The newest challenge posed by this threat is represented by the phenomenon of “foreign terrorist fighters”. Current estimates place the number of foreigners who have joined the ongoing armed conflicts in the Middle East between 20,000 and 30,000. How many of these foreign fighters also fall within the definition of foreign terrorist fighters (i.e. those travelling abroad with a “terrorist” intent) provided by UN Security Council Resolution 2178 (2014) is very difficult to assess. In primis because the resolution refers to “terrorists”, “terrorist acts”, and “terrorist training” without actually defining “terrorism” and thus leaving to each Member State the task to determine the breadth and the contours of this concept. Secondly because the text lacks legal certainty with regard to many other crucial aspects, e.g., the relationship between counter-terrorism and international humanitarian law, the interpretation of the term “State of residence”, and the risk of abuse of refugee status. These shortcomings not only jeopardize the ability to implement a uniform approach, but they also increase the likelihood of fostering abusive responses. This article argues that Resolution 2178 has not been adopted in a legal vacuum, on the contrary it extensively builds on the anti-terrorism framework established by previous Security Council resolutions and thus it inherits and exacerbates many old and unresolved issues. Ultimately, the present article seeks to determine to what degree the new set of binding obligations placed upon Member States to thwart the phenomenon of foreign terrorist fighters is effective and it discusses the extent to which it could enhance or hinder counter-terrorism’s compliance with international human rights law, international humanitarian law and international refugee law.