The Joint Defence Council was created to organise the allocation of military resources to India and Pakistan. This was a difficult task since much of the British Indian Army’s resources and personnel fell within India.

General Frank Messervy

Source: No 9 Army Film & Photographic Unit, Public domain, via Wikimedia Commons

There also an overestimation of the extent to which India and Pakistan would co-operate on military matters as a passage in Hastings Ismay’s (Viceroy’s chief of staff ) letter to Frank Messervy (General Officer Commanding-in-Chief Northern Command India) appears to indicate:

“…The Viceroy suggested the other day to the Indian representatives on the Joint Defence Council that they might assist in the defence of the Frontier with their air forces, but their reply was an emphatic negative.
I still cling to the hope that the Joint Defence Council, which is for the moment merely charged with the reconstruction of the Armed Forces, may in time2 develop into a body which will foster unity of doctrine, unity of equipment and unity of policy between India and Pakistan.
Meanwhile, the only thing that we, who are left in India, can do is to strive to get them to co-operate in any way that we can.“

Source: ‘Lord Ismay to Sir F. Messervy’ cited in Nicholas Mansergh & Penderel Moon (eds.), Transfer of Power, vol. XII, p. 664