Precis of naval appreciation of Australian naval defence. Begins.

(1) A Japanese attack upon Singapore would require at least fifty
thousand troops to undertake siege operations for some four or
five months in difficult country with all the disadvantages of a
long line of communications liable to interruption at any time if
Great Britain chose to send superior force. It is not considered
likely that Japan would embark upon such an enterprise.

Invasion of Australia is regarded as even less likely as this
would involve the despatch and maintenance of a large army with a
much longer line of communications, liable to be cut at any time
by a British fleet arriving in the area.

Apart from the fact that such an operation would be resented by
the United States, as long as there is a well-armed Australian
military force and a superior British fleet in being in any part
of the world it is needless to suppose such an enterprise would be
attempted.

(2) Long range action by submarine or raiding cruiser is always
possible but beyond temporary inconvenience by disturbing coastal
trade unlikely to cause much damage.

(3) Power of predominant fleet is exercised simultaneously in all
quarters of the globe in which it has bases irrespective of the
station it occupies at any given moment provided it is not
permanently tied to that station.

Naval situation at present quite different to that pertaining
during the last war. Admiralty contemplated fighting Italy in the
Mediterranean and German U-boats in the North Sea and Atlantic
with the aid of the French fleet which is very efficient and
strong as Italian and that Italy would have been defeated within a
few months.

Even if the result in Mediterranean had been long delayed, the
Admiralty were prepared to dose the Mediterranean at Gibraltar and
Suez Canal and sacrificing important interests in that area
proceeding to relief of Singapore or aid of Australia in the event
of serious attack.

With Italy neutral British fleet is again entirely mobile and
although not at present able to place superior battlefleet in
Japanese home waters it is possible if necessary to place a
squadron battleships at Singapore or Australian waters sufficient
to act as major deterrent on Japanese action so far from home.

This would of course be done from the moment that danger to either
Singapore or Australia developed in a manner which made their
protection a real and practical war need.

The Admiralty accept full responsibility of defending Australia or
Singapore from a Japanese attack on a large scale and have forces
at their disposal for these essential purposes.

The Admiralty most grateful to War Department for loyal and
clairvoyant strategy which has to the uninstructed eye denuded
Australia of naval forces. Assistance of Australian destroyers is
invaluable. The Admiralty regard the defence of Australia and of
Singapore as a steppingstone to Australia as ranking next to the
mastering of the principal fleet to which we are opposed and the
duty of defending Australia against serious attack would take
precedence over British interests in the Mediterranean. It is very
unlikely bleak choice will arise during next year or two.

Our naval strength is steadily improving as new battleships come
into service and there are no naval grounds for assuming (action)
which should prevent the despatch of Australian Army to decisive
battlefield where their name stands so high. Ends.

Am having a conference on the Far East statement and on above
statement on Monday afternoon and will cable you the result.

CASEY