405 Lord Cranborne, U.K. Secretary of State for Dominion Affairs, to Commonwealth Government
Cablegram 263 LONDON, 15 April 1941, 11.55 p.m.
IMMEDIATE MOST SECRET
Reference my immediately preceding telegram, paragraph 4 : The following are the tentative views of our military advisers:
References are to paragraphs in the telegraphic report of the Anglo-Dutch-Australian Conference - (1) Paragraphs 2 and 5: Influence of the United States in restricting freedom to move southwards.
Admittedly this is a matter of opinion. Some Japanese capital ships would certainly be available for the Malaya area but advisers doubt whether cruisers would be available in large numbers for attacking trade. They agree with the views expressed in paragraph 2 of the Report of the Conference.
(2) Paragraph 10(b): The scale of the attack on South Pacific Trade Routes:
The view expressed by the Conference appears to be a fair description of the likely scale of attack.
(3) Paragraph 10(c): Establishment of bases by Japan in New Guinea and Fiji area:
Advisers agree with the view expressed by the Conference, and note with satisfaction that a good deal has already been done, and that the matter is continuing to receive active consideration.
(4) Paragraph 10(d): A major attack on sea communications:
While not ruling out the possibility, advisers do not regard this course of action likely. A world wide redistribution of forces would be necessary in such an eventuality and it would, they consider, be useless to attempt to draw up plans now on account of the many variable factors which make it impracticable to forecast the forces which might be available over and above those already provided for. All that can be usefully done at present is to draw up plans on the basis of the most probable situation with the forces likely to be available.
(5) Paragraph 11 (a): Protection of troop convoys in the Indian Ocean: Initially we shall have only one capital ship in the Indian Ocean. To provide capital ship escort for convoys it will, at first, be necessary to accept reduced frequency in sailings. As regards further reinforcements, see the preceding paragraph.
Although capital ship escort appears desirable, it may be found possible, depending on actual course of events, to accept a lower scale of escort, e.g. two large cruisers.
(6) Paragraphs 23-25: Definition of act of war by Japan: Views of our military advisers have already been stated in paragraph 2(B) of my telegram of 21st March, Commonwealth of Australia 180, New Zealand 98.  They agree with the great importance attached to avoiding delay in reaching decision but the matter cannot be decided on military grounds alone and further study is being given to the problem in its political aspects. The advisers consider that advance notification to the Japanese Government of the interpretation we should place on certain actions by them is open to the objection that it will amount to pre-judging what would constitute an act of war by Japan. On military grounds they regard this as dangerous except in collaboration with the United States.
They agree with the Commonwealth Government's views as regards the Philippines.
(7) Paragraph 7: Australian Forces for Koepang and Ambon. The advisers agree that on military grounds it is desirable that these moves should be completed prior to the outbreak of hostilities but consider that such moves would provoke Japan to take counter measures. This again introduces political considerations which are being further studied. Advisers assume that control of troops at Ambon will be cleared up at the forthcoming conference.
(8) Progress of naval reinforcement east of Suez in the event of serious threat to Australia (question raised in Commonwealth of Australia telegram 187, paragraph 5). Our advisers' view is that no useful purpose would be served by attempting to draw up plans at Singapore for such an eventuality at this stage. To attempt to forecast the forces which might be available is quite impracticable and will therefore be misleading.