This paper evaluates the impact of EU border policies on migrant entry attempts, using administrative records of unauthorised crossings and a dataset on EU operations. The authors document a political cycle in enforcement, with efforts increasing near Member States holding the EU Council Presidency or facing elections, especially in eurosceptic countries. Using an instrumental variable strategy, they show that stricter enforcement reduces crossings along targeted routes, mainly land routes and migrants from non-refugee-sending countries, but has little effect on overall migration. They also find that the 2016 EU-Turkey deal decreased Eastern Mediterranean crossings while diverting flows to the Central Mediterranean. The results highlight the limited effectiveness of EU border policies due to national interests and route diversion.