Explaining Non-compliance in the EU Differentiated Integration: The Case of Transport and Infrastructure Obligations under the EU-Ukraine Association Agreement

External differentiated integration constellations, such as the EU Association Agreements (AAs) with Eastern Neighbours, require third states to conduct extensive regulatory approximation with EU rules. Nevertheless, compliance in EU external differentiation remains under-researched. In this vein, the article explains (non)-compliance in EU external differentiated integration through the prism of an integrated approach to compliance that brings together the enforcement and management perspectives. The research is based on the case study of Ukraine's fulfillment of its transport- and infrastructure-related obligations under the EU-Ukraine AA. It is found that Ukraine's low compliance rates stem from an array of factors attributable to both of the applied perspectives. The study testifies to the complementarity of the enforcement and management approaches in the research of compliance in EU external differentiated integration and points out the need for the Commission to combine 'carrots-and-sticks' approach with consultations and capacity-building to strengthen Eastern Neighbours' compliance with AAs norms.