During the early 1970s, NATO member states such as Norway, Denmark and the Netherlands repeatedly sought to use the Atlantic Alliance as a forum to confront Portuguese domestic and colonial policies. However, the larger members of the organisationincluding the USA, the UK, France and West Germanysuccessfully blocked their efforts. While the former expressed concern over the challenges posed by the Lisbon regime to NATO's credibility at home and abroad, the latter sought to preserve their interests and institutional cohesion in view of the challenges posed by détente. This fault line reflected core differences in the allies' perspectives about both Portugal and NATO itself. Drawing on extensive multiarchival research, this article examines the motivations and actions of various member states on the North Atlantic Assembly and the NATO Council ministerial meetings. It reconsiders the international dimension of the Marcelo Caetano dictatorship and the connection between the Cold War framework and the process of Portuguese resistance to decolonisation in Africa.