Thankless Task: Alliance Defense Investments and U.S. Public Support for War

Abstracts This article explores whether U.S. public support for using force to defend American allies is shaped by alliance burden-sharing, in the form of those allies’ efforts to invest in their own defense. Using four survey experiments conducted on samples of the U.S. public, this article finds that improvements in allied military capabilities can decrease U.S. public support by reducing the perceived need for U.S. intervention. These findings have implications for understanding alliance bargaining and U.S. public support for war. The results point to conditions under which alliance bargaining is more difficult due to the inherent incredibility of assuring allies that they will not be abandoned if they concede. Moreover, they suggest that research showing higher U.S. public support for war when the costs are lower, and ease of victory is higher, overlook an important confounding factor.