The Ministry of Defence
As the head of the MOD, the Secretary of State is responsible for the formulation and conduct of defence policy, and for providing the means by which it is conducted. Although the MOD is responsible for high level policy, it does not command forces directly. The Secretary of State is supported by three junior ministers who have responsibility for the Armed Forces, Defence Equipment & Support and Veterans Affairs.
The highest military post within the MOD is the Chief of the Defence Staff (CDS). This position is filled by a senior officer from one of the three Services. CDS is the professional head of the Armed Forces and is the principal military advisor to the Secretary of State. Alongside him sits the top Civil Servant known as the Permanent Secretary (PUS). His areas of responsibility are finance, planning and administration of the MOD. CDS and PUS each have a deputy; The Vice-Chief of the Defence Staff (VCDS) and 2nd PUS. Together VCDS and 2nd PUS are the joint heads of the Central Staff, the heart of the Ministry of Defence planning and policy departments.
A number of other defence-related departments and agencies are also controlled by the MOD. These include Logistics, Procurement and Intelligence. These organisations have members of all three armed forces working alongside each other and are often referred to as 'Tri-Service' departments.
Within the MOD, each of the three Services has a permanent Chief of Staff. The Chief of the Air Staff (CAS) has the rank of Air Chief Marshal. CAS is the senior advisor to the Chief of Defence Staff on matters relating to air power. CAS has a deputy, Assistant Chief of the Air Staff (ACAS).