US policy-makers have coalesced around the need to develop a riskbased approach for managing strategic effects of cyber attacks. This paper uses graph networks of US air infrastructures from the Department of Transportation to develop the Strategic Disruption Index (SDI), a means to assess the loss of effective transportation network capacity of passengers resulting from various cyber attack scenarios. Dynamic effects are measured using an agent based model to assess the ensuing propagating air passenger delays. Results from this analysis show strategic effects are influenced by airport and airline network structure and induce dynamic effects across the entire sector. We find that the largest national strategic effects are generated through the disruption of key vendor relationships that can potentially affect multiple private operators simultaneously. Policy-makers who are charged with developing means of measuring national risk can apply this approach to evaluate strategic impacts to any number of domestic or international transportation networks. They can also use the approach to compare impacts between disparate infrastructure networks to prioritize resources that best limit the range of strategic risk.