Considering the wide range of missions the force may be in charge with, its composition and size cannot be defined in advance. In fact, the force will not be established on a permanent basis, but will be assembled on a case-by-case basis and tailored to the mission. It will be built up amongst the capabilities made available by the participating nations, the most suitable ones for the operation to be conducted.

The size of EMF may range from a small Task Group to a large Task Force including carrier and amphibious groups, escorts and support vessels. Furthermore, maritime patrol aircraft, mine countermeasure units, submarines or other types of naval units could be employed, depending on the mission and the relating tasks to fulfil. From the moment when the member nations take the decision to intervene in a crisis by employing the EMF, the CIMIN directs COMEUROMARFOR to activate the force. After consultation with the CIMIN, CEMF and national authorities, participating nations define the volume and nature of their involvement. Subsequently, they assign units to EMF. COMEUROMARFOR assembles the assigned units and gets their operational control as required.