The Swedish government is procuring high-performance radar stations with the capability to detect and track ballistic missiles. This paper discusses the possibility of such sensors, based in Sweden, to contribute to the ballistic missile defence of Western Europe and North America. The analysis is limited to geographical factors, given some basic assumptions about radar performance. It is concluded that, since many long-range ballistic missile trajectories from countries known to possess ballistic missiles towards targets in Western Europe and North America pass over or in the vicinity of Swedish territory, radar sensors located in Sweden would be geographically well placed to detect and track such missiles. This in turn opens up the possibility to contribute sensor data to a Western ballistic missile defence system.