NATO has a particular relationship with Great-Britain : it is both a most British institution and perceived as essential to British security. To the eyes of British leaders, NATO thus appears to be the sole legitimate institution capable of representing a Western strategic presence against the new stakes and threats to world security. Several paths of thinking are contemplated ; the elaboration of a new Strategic Concept, notably by integrating the problematic of the EU-US relationship or a new, closer relationship between these two players, defining the Global Approach and Global Defence and integrating them within a planning instrument such as SHAPE, and finally modernising armed forces. London’s challenge then resides in the deep discrepancies within the Alliance itself about its identity. The difficulty lies in maintaining a systematic, legitimate and coercive organisation model, while adapting it to widen its influence and its range of action.