The Military Staff of the European Union (EUMS) is the directorate-general of the European Union's (EU) External Action Service (EEAS) that contributes to the EU's Common Security and Defence Policy (CSDP) by providing strategic advice to the High Representative (HR/VP) and commanding operations through its Military Planning and Conduct Capability (MPCC) operational headquarters. From the end of 2020, the MPCC will be capable of running executive operations of up to 2,500 troops, i.e. the size of one EU battle group, as well as 3 non-executive missions.

The European External Action Service (EEAS) is the diplomatic service and combined foreign and defence ministry of the European Union (EU). The EEAS is led by the High Representative for Foreign Affairs and Security Policy (HR/VP), who is also President of the Foreign Affairs Council and vice-president of the European Commission, and carries out the EU's Common Foreign and Security Policy (CFSP), including the Common Security and Defence Policy (CSDP).