Sweden has despite not being a member of any military alliance had a long tradition of military cooperation with other countries. We have since the 1990s been a member of NATOs extended voluntary cooperation program Partnership for Peace and have conducted many international peace keeping operations with other countries. Because of the recently harsher political climate in Europe Sweden has signed a host nation support agreement with NATO. We have declared our willingness to give military aid if any of our neighbouring countries are attacked and ratified the latest EU-carter. Which encompass articles of collective defence. Even though we have a high degree of military interoperability with many of our neighbouring countries frictions will non the less occur in the case of collective military operations. This essay tries to identify the nature of these frictions to enable Sweden, either to trough more adaption or planning, mitigate these potential future frictions. The result shows that the largest source of frictions are the behavioural aspects of multinational cooperation. Which encompasses aspects of both military culture and doctrine.