This article analyses why the proposal of launching Common Security and Defence Policy (CSDP) operation Sophia to fight against human trafficking and avoid further drowning in the Mediterranean Sea was adopted soon after the tragic event of the 19 April 2015 – when more than 700 people died in the sea in one night – and not before. Using an agenda-setting perspective, we argue that a key explanatory factor is the institutional turnover that took place at EU level in November 2014, especially the appointment of Mogherini as EU HR. This article applies the Multiple Streams Framework of Kingdon to analyse the factors that allow an issue to be put high on the agenda and proves the relevant impact of the appointment of Mogherini as EU HR on the decision to launch Sophia. It also uses the framework developed by Princen to identify strategies used by political actors for putting an issue on the EU agenda and shows that Mogherini successfully performed the strategy of ‘claiming authority' for EU action. This article sheds lights on the impact of the concern, political background and strong commitment of the EU HR in agenda-setting dynamics at EU level.