Traditionally seen as an interlocutor between Europe and the US in transatlantic security relations, the UK's engagement with the training of the Afghan National Police (ANP) through the concurrent EU and NATO missions presents an interesting case of foreign policy decision-making. Although a logic based on broader British orientations about the roles of the two organisations expect that the UK's primary institution of choice would be NATO, London supported both missions in providing international policing assistance to Afghanistan. Adopting an operational overlap perspective, this article seeks to explain the UK's strategic behaviour vis-a-vis the EU and NATO training missions that have been simultaneously involved in overlapping tasks, despite the initial intention that the two missions would undertake different and complementary roles. Analysing evidence from the UK Parliament and Government, US diplomatic missions, the EU and NATO, as well as interviews with former UK and NATO officials, this article argues that while providing training to the Afghan police, London focused on these missions' practical outputs rather than preferring an organisation of choice as such. This strategy is mainly guided by the UK's concern to uphold counter-narcotics enforcement in Afghanistan and to fulfil transition tasks during the incremental withdrawal of British troops.