The Chief of Defence Staff heads the Department of Military Affairs but commands none of the three Services

Background

The Union Cabinet approved the creation of the post of Chief of Defence Staff in the rank of a four-star General, with salary and perquisites equivalent to a Service Chief.
The Chief of Defence Staff heads the Department of Military Affairs, created within the Ministry of Defence, and functions as its Secretary.
That Department deals with the Army, the Navy and the Air Force, with the Integrated Headquarters of the Ministry of Defence, with the Territorial Army, and with procurement exclusive to the Services except capital acquisitions.
Its mandate also covers jointness in procurement, training and staffing, the restructuring of Military Commands including joint or theatre commands, and the promotion of indigenous equipment.
The Chief of Defence Staff is additionally the Permanent Chairman of the Chiefs of Staff Committee and the Principal Military Adviser to the Raksha Mantri on all tri-Services matters, while the three Service Chiefs continue to advise the Minister on matters concerning their own Service alone.
The Chief of Defence Staff exercises no military command, including over the three Service Chiefs, so as to be able to provide impartial advice to the political leadership; the one command the decision does give the post is over the tri-service agencies, organisations and commands related to Cyber and Space.
The proposal is traced to the Kargil Review Committee headed by K Subrahmanyam, which in 1999 recommended a review of the National Security Framework, and to a Group of Ministers that recommended the post in 2001; the Prime Minister announced the Government's intention to create it in an address to the nation on 15th August 2019.
For a smooth transition, 159 personnel were moved from the Department of Defence to the newly created Department.