ABSTRACT
This chapter focuses on one particular body of work that has emerged from the field of critical security studies since the mid-1990s, namely Securitisation Theory (ST) most prominently associated with the Copenhagen School. It then argues that ST provides a sophisticated toolbox for analyzing the origin, evolution and transformation of North Atlantic Treaty Organization (NATO). Securitisation helps to understand how cooperation 'took a unique form as the North Atlantic alliance developed into an organisation NATO uncharacteristic for alliances'. The chapter also summarises how ST provides a useful framework for theorising and analyzing the Alliance. It further provides a brief introduction to ST based on its three key pillars: de-/securitisation, security sectors and regional security complexes. Finally, the chapter focuses on three periods of NATO's evolution: the foundational years of NATO in the early 1950s, detente as expressed by the Harmel Report in 1967 and NATO's transformation after the end of the Cold War in the early 1990s.
