In light of Islamic State’s decreasing military power and growing emphasis on a decentralised operational strategy, the threat posed by foreign fighters is shifting, with some aspects becoming less threatening as others become more salient. This Policy Brief provides a concise outline of four main threats related to the issue of foreign fighters with the aim of clarifying the parameters of the phenomenon in its current manifestation: the travel of foreign fighters, their return to their countries of residence, the threat posed by lone actors and sympathisers who carry out attacks at home, and finally, an increasing polarisation of society. It is argued that policymakers need to take into account the second and third order effects that targeting one of these aspects may have on the others in order to effectively counter a multi-dimensional phenomenon.