To act as a Union: Explaining the development of the EU's collective foreign policy

It is difficult for states to cooperate on issues related to international peace and security. Yet, ever since 1970, the EU member states have succeeded to gradually intensify their foreign policy cooperation and increasingly act in unison towards the rest of the world. This PhD thesis seeks an explanation to this trend. It does so by initially painting a picture of when, in time, the volume and content of the Union's collective foreign policy changed during the thirty-year period between 1970 and 1999. It then proceeds to use this picture when investigating three theoretically guided questions: Is it primarily the successive institutional changes that have enabled the EU members to agree more frequently at times? Are they perhaps periodically driven closer together as the threats facing the EU have changed? Or, is it recurrent disagreements with the world's sole superpower that generates additional political will to act as a Union? The findings suggest that changing threats are not the most important driving force, and that institutional modifications have rarely been immediately followed by any substantial changes in the Union's foreign policy. Instead, the political will to cooperate has periodically increased when EU members have disagreed with American strategies on international security management. The new levels of cooperation have often been ?locked in? by new institutional changes, before another transatlantic dispute has erupted and highlighted ? again ? the need to balance American influence. These conclusions are eventually illustrated and corroborated by an in-depth study of events during the period surrounding the Iraq war in 2003.