153 Commonwealth Government to Lord Cranborne, U.K. Secretary of State for Dominion Affairs
Cablegram 765  CANBERRA, 2 December 1941
The following sets out the views of His Majesty's Government in the Commonwealth of Australia with regard to the possible contingencies emanating from a Japanese movement.
The cases of Japanese aggression which should now be considered are five in number:-
(1) Intensification of attack by Japan against China, especially Yunnan and Burma Road.
This does not amount to new Japanese aggression, but to accentuation of existing undeclared war. However, it does create a special situation because United States is very sensitive and sympathetic as to the position of China. We think this first case of Japanese aggression is clearly one where we should be content to follow the lead of United States and not to declare war against Japan unless United States armed intervention is certain. We should, of course, continue to give China support short of declaring war against Japan, such support including provision of volunteer air forces, of aircraft equipment and supplies.
(2) Japanese attack on Thailand.
Admittedly this is a difficult question. Attitude of United States seems lukewarm, as witness their refusal to give Thailand economic assistance or military equipment.
(a) We adhere to our decision of yesterday (telegram 763)  namely that if Japanese armed threat against Kra Isthmus is definitely established, it would be advisable to follow advice of competent military authority and, subject to conditions mentioned in our telegram, to occupy the region referred to;
(b) The principle of that decision is that, in the opinion of the competent military authority, the strategic defence of Malaya does require such an occupation;
(c) In the event of the Thais resisting Japanese aggression elsewhere in Thailand and appealing to us to assist, our refusal to assist would undoubtedly have a very bad effect upon world opinion. On the other hand, our physical resources are limited and at present we do not see how we could intervene effectively except in Kra Isthmus to the limited extent already mentioned;
(d) The conclusion is that with regard to Thailand, except in the case of Kra Isthmus, regarded as an integral portion of the defence of North Malaya, we should not give armed support except with the assurance of United States active co-operation.
It is true that the decision to occupy Thailand territory in the Kra Isthmus may well lead to war with Japan and perhaps Thailand also, but the risk of this may fairly be run in view of the strategic considerations.
(3) Japanese attack against Russia.
The position of Russia is a special one because of British-Russian alliance , and because Japan is an active Axis power. In event of Japanese attack against Eastern Siberia, our view-already expressed in 714 to Secretary of State 41S that there should be a declaration of war by Britain against Japan. Public opinion would not tolerate anything less. We think Russia should be informed that question has arisen, and should be asked to undertake that, if we are involved in war against Japan in the Pacific due to southward aggression, Russia will consider herself at war with Japan. Such a reciprocal arrangement, if suitably notified to Japan, should in itself be a valuable deterrent against Japanese aggression. The first part of this paragraph should be contingent on the second part.
(4) Japanese attack against Netherlands East Indies.
For twelve months the Netherlands Government has been pressing for a British declaration of automatic armed support in case of Japanese attack on N.E.I. Australia feels very strongly that we should at once give such an assurance of armed support and do so irrespective of United States attitude. In return we should seek a definite commitment from the Netherlands that if we are at war with Japan as a result of Japanese aggression in the Pacific, the Netherlands Government will also be at war with Japan. Here, as in the case of Russia, the bargain should be reciprocal.
(5) Portuguese Timor.
It is essential that in the event of Japanese attack on this territory, Britain should declare war irrespective of United States attitude. Portuguese Timor is the entrance door to Australia. Secretary of State's message 766  suggests that Portugal expects declaration from us and that she on her part is willing, within her very limited powers, to resist Japan and declare war upon her. We think a definite understanding with Portugal should now be negotiated upon this footing.
As we have asked, a decision should now be taken in relation to five above types of aggression. Of course, such decision will itself be subject to alteration in the event of change in international or strategic situation.