Despite diverging perspectives and interests, the EU's Member States have forged a common response to the Russia–Ukraine crisis. How can this be? In this article, we suggest that in order to explain the Member States' ability to reach agreement in this case, we must take into account the normative force of the arguments presented in favour of a common response. We find that neither a concern for security (as would be expected from a realist perspective) nor the institutionalization of a norm of cohesion (which would be the constructivist expectation) triggered the collective response. Instead, agreement was established due to concurrence over a fundamental breach of the Ukrainians' right to self‐determination. This finding is significant in theoretical terms in that it confirms that norms may trump interests. It does not, however, allow for definite conclusions with regard to the robustness of integration in EU foreign policy.