As joint, combined and Civil-Military exercises are becoming increasingly common, the need for security in collective mission simulation is growing. SISO has developed the Distributed Simulation Engineering and Execution Process (DSEEP) standard that provides a recommended process for development, integration and execution of federated simulations. Security aspects need to be managed throughout the DSEEP process. This paper offers three perspectives on this, based on the NATO MSG-080 work: • A holistic approach, mapped to DSEEP, is presented. It discusses how training goals and security goals may conflict. It discusses possible resolutions as well as situations where security concerns may limit the training that can be provided. • A real-life use case where a UK integration into the US Joint Training and Experimentation Network (JTEN), including security aspects, is mapped to DSEEP. This provides a deeper insight into the issues real federations may encounter and presents experiences and some advice. • Finally a closer look at security and DSEEP is given. The focus is to support the selection and deployment of security procedures and technical security measures with focus on DSEEP step three and four. These perspectives are presented as input to the SISO community in general and the SISO Security in Simulation (SiS) study group in particular.