Pledge and Forget? Testing the Effects of NATO's Wales Pledge on Defense Investment.

This article examines whether NATO's 2014 Wales Pledge on defense spending—a public agreement without formal enforcement mechanisms—has effectively influenced member states' defense expenditures. Using a difference-in-differences research design and a purpose-built dataset comparing NATO allies to non-NATO European Union (EU) members, particularly focusing on the Nordic states (Denmark and Norway as NATO members versus Finland and Sweden as non-members during the study period), the analysis finds that the Wales Pledge has led to significant increases in both overall and equipment-specific defense spending among NATO allies. Qualitative evidence from national strategic documents and interviews supports the conclusion that NATO's institutional framework and peer pressure mechanisms, rather than external threat perceptions alone, have driven these spending increases. The study highlights the role of consensus-driven, transparent international agreements in shaping state behavior and suggests that NATO membership constrains burden-shifting tendencies more effectively than informal or unilateral pressures.