Abstract
<jats:p xml:lang="en">The CSDP is a key pillar of the EU’s external action, originating from the 1998 Saint-Malo Declaration, which advocated for Europe’s autonomous defence capabilities. Initially established as the ESDP under the Maastricht Treaty, it was redefined by the 2009 Lisbon Treaty, gaining institutional strength. Since then, the EU has launched various civilian and military missions, supported by tools like the European Defence Agency and PESCO. Brexit marked a turning point, as the departure of one of the EU’s strongest military powers challenged the credibility and effectiveness of the CSDP. Yet, it also accelerated efforts for deeper defence integration and strategic autonomy. This article examines the CSDP’s evolution and critically assesses how Brexit reshaped the EU’s defence policy and its role as a sovereign security actor.</jats:p>