Abstract: Naval air defence is a complex multi-dimensional problem, requiring complex and expensive equipment. In the current military environment, both missiles (hardkill) and decoys (softkill) are used against contemporary threats. These systems all influence the same spectral bandwidth and are often required simultaneously. Only suitable coordination will allow these systems to be used to full performance against the threat. Another consideration is the signature and manoeuvre capability of the defending platform and its influence on the hardkill and softkill systems. This paper provides an overview of the problem of the threat and coordination of softkill and hardkill as an introduction to a series of papers on the subject of hardkill-softkill coordination.