38 Mr S. M. Bruce, High Commissioner in the United Kingdom, to Mr R. G. Menzies, Prime Minister
Cablegram 635 LONDON, 8 August 1941, 8.33 p.m.
MOST IMMEDIATE FOR THE PRIME MINISTER MOST SECRET
Questions of the highest policy have now to be determined and I
send you the following thoughts. Problem as I see it is as
There would be general agreement that Japan having under her
agreement with Vichy obtained and occupied bases in Indo-China
[the]  United States, United Kingdom and Dutch Governments
should now warn the Japanese Government that any extension of its
southward movement into Thailand (Siam) will be resisted. The
difficulty with regard to this course is the doubt whether the
United States would be prepared to join in any such warning and we
have to consider what our course should be in the event of this
proving to be the case. The alternatives would appear to be:
(1) Do nothing and take no action unless we are attacked.
(2) Issue the warning without United States being associated with
(3) Issue no warning but seize KRA Peninsula immediately upon any
infringement of Thai territory by the Japanese.
(4) The seizure of KRA Peninsula immediately without waiting for
any further action by Japanese.
In considering these four alternatives our objectives must be kept
clearly in mind:
(a) To avoid war with Japan.
(b) To ensure United States will support us if we do become
involved in war.
With regard to (1) I doubt if this is the most likely method of
avoiding war. Indications are that Japan may follow up what she
has got away with in Indo-China by testing out how far she can go
in Thailand. If she does and is allowed to do so without any
interference she will probably go so far [as] to imperil our vital
interests to such an extent as to make war inevitable.
In considering this alternative the effect of our adopting it in
United States, Russia and China has to be weighed. United States:
Although we would consider that the negative attitude of United
States was the reason for our doing so I believe that we would
harm our cause in United States by sitting down under Japanese
pressure and weaken the prospects of United States co-operation.
U.S.S.R.: Letting Japanese strengthen their position in the Far
East leaving them free to attack the Russians would not strengthen
our position vis-a-vis U.S.S.R. China: What applies to Russia
applies with double force to China and the Chinese will to resist
might be seriously reduced.
With regard to (2)-this possibly offers the best prospect of
If Japanese do not want war but are only testing how far they can
go without precipitating it, the warning will halt them. If they
are bent on war it will make no difference and will at least
prevent our landing into war after Japan has seized further bases
making our defence of Malaya more difficult. To my mind this
course offers the best prospect of early United States
intervention. Warning would be given with knowledge of United
States-obviously we could not take this course if the United
States had protested against it-and if, as a result of it,we
became involved in war I believe that the United States would soon
be in with the support of public opinion.
With regard to (3) this course has a certain attraction but has
the danger that the first infringement of Thai territory by Japan
might be the seizure of KRA Peninsula and we might find ourselves
With regard to (4) this is probably the wisest course from the
military point of view but probably makes war inevitable, and if
it did our seizure of Thai territory gives Japanese an excuse for
similar action. The effect on American public opinion might also
After carefully weighing all the alternatives I believe (2) is the
right one. There are so many factors to be weighed in considering
the above four alternatives that I hesitate to express a view. I
will, however, risk doing so.
[AA : A981, JAPAN 185B, ii]