An outstanding academic career in engineering risk assessment and probabilistic methods applied to a wide range of infrastructure/engineering systems, including climate change, brought Prof Stewart to advising on risk analysis for terrorism issues and counter-terrorism methods. Consulted by Australian and US upper-echelon defence experts, he has presented cutting edge risk analyses, including rational expenditure of public funds. His ideas have been presented in 3 seminal books and many scientific and engineering papers, and have brought engineering and scientific expertise into the public policy domain.