The assignment of a radioactive source to a security group is most effectively achieved by
using the outcomes of the threat assessment. This allows most flexibility and specificity to
account for the variability in threat levels and security environments within Member States. It
also permits different choices of security groups for sources in the different stages of their life
cycle. Alternatively some countries may perform countrywide threat and vulnerability
assessments and make allocations of sources to security groups based on these assessments.