Ups and downs in NATO’s fortunes are nothing new, and predictions of NATO’s demise are almost as old as the Alliance itself. What is remarkable is not the Alliance’s decline but its longevity. NATO has outlasted the Warsaw Pact by some three decades. Other Cold War alliances – the South East Asia Treaty Organisation (SEATO) and the Central Treaty Organisation (CENTO) - passed into history in the late 1970s. All of which begs the question: why has NATO persisted when other alliances have fallen by the wayside? There is already some excellent scholarship that addresses this issue. As NATO approaches another milestone – the adoption of its fourth post-Cold War Strategic Concept – it is worth examining the question once more.