This report investigates how drones, and particularly drone swarms, may affect the future of warfare and civil defence (in Swedish, befolkningsskydd). The report shows that civil defence/civil protection organisations must expect that antagonists will use various forms of drone swarms or a mixture of drones and other weapon carriers against, for example, critical infrastructure and other civilian objects. Swarms could be used locally, as part of denial attacks, or in terrorising fashion towards the state as a whole. From the war in Ukraine, we already see examples of such uses. This trend might develop further, seeking to gain asymmetric advantages for coercive purposes by threatening to carry out attacks against civilian objects and infrastructure with large numbers of drones and other weapons. Countermeasures are already available and could be adopted by civil defence/civil protection organisations to mitigate risks, but they need to be considered from the context of war and with swarming capability in mind. Drone swarms themselves could also be useful for civil defence in various ways. Developments in drone swarm technology and capabilities should be followed from a civil defence perspective, and there is a need for continued research in numerous areas. Important examples include the development of surveillance and warning systems for drones and drone swarms. Method development for surveillance and rescue tasks using drones and drone swarms would also be beneficial in peacetime crises and for civilians during armed conflict. In addition, social science studies on risk awareness, public fear, and asymmetric warfare related to technological leaps such as drones with swarm capability would also be beneficial.