Although many EU member states experienced large scale terrorist attacks and both national and EU policymakers have repeatedly acknowledged the need to tackle the apparent contradiction between borderless terrorism and national counterterrorism measures, a genuine supranational EU counterterrorism response has not emerged thus far. In this article, we explore why this has been the case. Via a set of proxy indicators, we operationalize and test three key variables derived from differentiated integration theory, which suggests that the lack of horizontal and vertical integration in the EU’s counterterrorism policy ought to be the result of high and asymmetric politicization, asymmetrical interdependence, and little preference convergence across EU member states. Our findings indicate that although all of these variables did influence integration in the first fifteen years of EU counterterrorism policy (2001–2016), only one variable (interdependence) acted exactly as expected by differentiated integration theory.

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欧盟与反恐斗争：差异化的一体化理论视角

尽管许多欧盟成员国都经历了大规模的恐怖袭击，国家和欧盟的政策制定者都一再承认需要解决无国界恐怖主义与国家反恐措施之间的明显矛盾，但迄今为止，真正的超国家欧盟反恐应对措施尚未出现。在本文中，我们将探讨为什么会出现这种情况。通过一组代理指标，我们对源自差异化一体化理论的三个关键变量进行操作和检验，这表明欧盟反恐政策中缺乏横向和纵向一体化应该是高度不对称政治化、不对称相互依存和欧盟成员国之间的偏好趋同。