243 Mr R. G. Casey, Minister to the United States, to Department of External Affairs
Cablegram 1240 WASHINGTON, 30 December 1941, 3.30 p.m.
MOST IMMEDIATE MOST SECRET
My telegram 1237. 
1. Last night joint United States-British planning staffs worked again on [proposed ] 'letter of instructions'. Most important matters discussed were as follows.
2. It is now proposed that geographical limits of the South-west Pacific theatre should be a line roughly north and south to westward of and including Burma, Malaya, Sumatra thence to about Onslow on Western Australian coast, thence [north] easterly round the Australian coast, (but excluding the mainland of Australia altogether) [to] Cape York, thence in a northerly direction along the boundary between Dutch New Guinea and Papua and Mandated Territory of New Guinea and northward to equator, thence roughly north-west (to north-east of the Philippines) to the coast of China.
3. Above means that instead of a portion of Northern Australia being included in the theatre, the whole continent of Australia and the Australian half of New Guinea is proposed to be excluded.
This means that all of the forces in Australia and Australian New Guinea would be under Australian command and not under the supreme commander.
4. It is suggested, however, that all the forces in Australia that may be designated or allotted to or in support of the South-west Pacific theatre should be under general strategic control of the supreme commander.
5. It is further proposed that the area which includes Australian New Guinea, Bismarck Archipelago, Solomon Islands, New Hebrides, New Caledonia and Fiji should be within 'Australian area', that is excluded from South-west Pacific theatre and also excluded from area in Pacific for which United States fleet based at Honolulu is responsible.
6. In the absence of specific instructions from you (which I realise in the circumstances you have had no opportunity of sending me) I am basing my representations on the viewpoint expressed in Prime Minister's Dept. telegrams No. 153  and 154 , to the effect that Australian Naval and Air resources are quite insufficient to enable Australia to maintain effective control over area mentioned in paragraph 5 above.
7. There are other suggested amendments of [lesser] importance to above which I will deal with later.
8. You should know that all matters in connection with unifi[ed] command in South-west Pacific theatre are being worked out between United States and British staffs only. I am not in any way in on the discussions, nor is anyone else connected with any Government other than those of United States and Britain. I am keeping myself as closely informed as possible through British and American sources and information that I have sent you in this and preceding telegrams is not (I have every reason to believe) available to anyone else outside British and American staffs actually involved in discussions.
9. In view of importance of matters in this telegram (particularly paras. (5) and (6) above) I am venturing to put forward views in para. (6) both to American and British on authority of P.M.
telegram 153 and telegram 154, but am making it clear that, until I have specific instructions from you, I am doing so in a personal way. My belief is that it is important to have this matter brought to notice while 'letter of instructions' is in formative stage.
10. In accordance with Churchill's original telegram to Prime Minister  on Unified Command proposals you would have had no knowledge of the proposed content of 'letter of instructions' until they were fully agreed upon between Britain and America when they would be more difficult to have altered.