The EU’s common security and defence policy (CDSP) is an integral part of the EU’s common foreign and security policy (CFSP). It includes the progressive framing of a common EU defence policy, aims at allowing the EU to enhance its military capacities and deploying missions outside the EU for peace-keeping, conflict prevention and strengthening international security in accordance with the principles of the United Nations Charter. The CSDP shall respect the obligations of certain member states which see their common defence realised in NATO. It is covered by Articles 42-46 of the Treaty on European Union.
Decisions relating to the CSDP are taken by the Council of the European Union by unanimity. However, there are some exceptions like for instance when the Council adopts some decisions implementing an EU decision or for some decisions relating to the European Defence Agency (EDA) and permanent structured cooperation (PESCO), where decisions are taken by qualified majority voting.
The EU’s High Representative for Foreign Affairs and Security Policy is responsible for proposing and implementing CSDP decisions.
Source: EUR Lex Glossary