Intertwined economies are part of it but I think people underestimate the importance of norms. EU leaders and ministers are regularly in meetings together. Wh

Intertwined economies are part of it but I think people underestimate the importance of norms. EU leaders and ministers are regularly in meetings together. When there is a crisis now the reaction of all EU leaders is to hold a conference for them to hash out how to deal with the situation. This establishment of the norm of talking whenever there's an issue is very powerful.