The General Secretariat for Defence and National Security (SGDSN) is an interministerial body placed under the authority of the French Prime Minister which assists the head of government in designing and implementing security and defence policies. It provides advice and support to the political decision-making process. Its areas of expertise include all strategic defence and security matters, such as military programs, nuclear deterrence, internal security as part of national security, economic and energy security, counter-terrorism and crisis response plans.

SGDSN fulfils three main missions :

• it is responsible for monitoring security threats, preparing governmental plans and coordinating public crisis management ;
• it advises the government, and takes part in the drafting of bills and decrees relating to matters of security and defence ;
• it carries out a variety of operational tasks, ranging from security clearance and classified document management to the protection of governmental communications (via the Centre de transmissions gouvernemental) and cybersecurity. A national agency within SGDSN (ANSSI, Agence nationale de la sécurité des systèmes d’information) is specifically in charge of the latter.

SGDSN also oversees the Institut des hautes études de défense nationale (IHEDN) and the Institut des hautes études de la sécurité et de la justice (INHESJ).