The Council of the European Union is an Institution with a formal legislative role. It is composed of different configurations of national Ministers (one per country). The exact configuration of each meeting depends on the topic under discussion.
The Minister for Defence, Alan Shatter TD, will host an informal meeting of EU Defence Ministers. The working session of this meeting cover all topics related to the Common Security and Defence Policy.
For more information, please see: http://www.eu2013.ie/events/event-items/informaldefencecouncil-20130212/