Neutrality is not a static concept but has evolved significantly, reflecting changes in political, military, and economic contexts over time. This paper argues how neutrality has changed in Switzerland, Sweden, and Finland, particularly in response to the invasion of Ukraine. These European case studies highlight neutrality as a complex, dynamic and multifaceted concept, which has transitioned from a rigid principle to a dynamic and adaptable practice across military and political realms that evolves in response to shifting geopolitical contexts, public opinion and growing alliances. This paper reveals how increased spending, expanding alliances and shifting public opinion have redefined the concept and practice of neutrality in Europe By redefining the territorial boundaries of NATO’s Article 5, which commits members to collective defence measures, new borders with potential adversaries are introduced, creating new vulnerabilities and opportunities for defence.  The paper will begin by giving a brief account of the historical development of neutrality in Europe in the 17th and 18th centuries to contextualised the following discussions. For each case study, the dynamic nature of neutrality will be revealed, with a particular focus on developments following the invasion of Ukraine.