Motivated by US Secretary of Defense Robert Gates' farewell address to NATO, this article investigates whether NATO burden-sharing behavior has changed during the last ten years. Based on a Spearman rank correlation test, we find almost no evidence that the rich NATO allies shouldered the defense-spending burden of the poor allies during 1999–2009. In 2010, there is the first evidence of the exploitation of the rich. When allies' defense burdens are related to defense benefit proxies, a Wilcoxon test finds that there is no concordance between burdens and benefits after 2002. This is indicative of a less cohesive alliance, in which allies are not underwriting their derived benefits. We also find that allies' benefits, which are tied to their exposed border protection and terrorism risk, motivate defense spending. Allies' benefits, based on economic base and population, are less of a driver of defense spending for most NATO allies. We devise a broad-based security expenditure burden that accounts for defense spending, UN peacekeeping, and overseas foreign assistance. In terms of this security burden, there is evidence of the exploitation of the rich by the poor beginning in 2004. Our findings indicate a two-tiered alliance that faces significant policy challenges.