The Defence High Command (Spanish: Alto Estado Mayor, AEM) was the principal staff body of the Spanish Armed Forces during the Francoist regime and the transition to democracy.

[1][2] The AEM was created on 30 August 1939 with the objective of having a "body of coordination, study and information, which would provide to the supreme command the elements of suitable judgment for the orientation of its designs".

In this way the Defence High Command is constituted with the following tasks: For this it was necessary on the one hand the appointment of a General-Chief who would be a member and secretary of the National Defense Junta, and on the other hand the creation of a secretariat and three sections: a military, an economic and an informational.

That is why a new military intelligence agency began operating, the so-called "Third Information Section of the Defence High Command [es]" (SIAEM).

However, due to problems of coordination between the various counterintelligence mechanisms of the time, it was decided in 1945 to divide the powers: the Defence High Command would be in charge of espionage and counterintelligence of military character both inside and outside the country, while the Ministry of the Interior would be in charge of the internal security of the country, and the rest of the ministries would collect the general information according to their needs.