An expanded investigation of alliance security free riding

This paper provides an expanded analysis of NATO security burden sharing by including a variety of conglomerate security terms that involve subsets of military expenditure (ME), UN and non‐UN peacekeeping contributions, global health spending, UN environmental support, and official development assistance. In so doing, we identify components of security spending that promote or inhibit free riding on allies' security spillovers. Additionally, we examine security burden sharing when the NATO alliance is conceptually augmented to include three key Asia‐Pacific allies – Australia, Japan, and the Republic of Korea. The paper's statistical tests for security burden sharing rely on spatial‐lag panel models that account for ally connectiveness based on alliance membership, contiguity and US power projection, and allies’ relative locations. Security subsets containing ME display robust free riding or reliance on other allies’ security spillovers, while security subsets not containing ME indicate allies responding positively to security spillovers.