Following for the Prime Minister from the Prime Minister.

Recent intelligence indicates that the Japanese are moving a
considerable fleet to Singapore. The position is not yet entirely
clear, but four battleships and one aircraft carrier are believed
to have arrived and we have reason to think that the fleet at
Singapore may be built up to seven battleships, two fleet
carriers, with some cruisers and destroyers. The remainder of
their fleet is likely to be stationed in the Pelews.

2. We have carefully studied this new development which has some
interesting features. The Japanese must have appreciated that
Truk, where normally they stationed half of their fleet, was
becoming too exposed and they evidently withdrew from there before
the recent American attack. [2] The choices with which they were
then faced were either to concentrate the whole of their fleet in
Japanese waters, or to move a portion of it to Singapore using the
Pelews as an advanced base. They appear to have chosen the second
alternative, their reasons being probably the following:-

(a) The concentration of the whole of their fleet in home waters
would be bad for both naval and civilian morale and would
surrender the initiative to the Allies.

(b) The Japanese are now extremely short of tankers and Singapore
lies close to the source of their oil supplies in Sumatra.

(c) The Japanese fleet at Singapore is equally well placed for
operations in the Pacific or in the Bay of Bengal. Singapore has
the best docking and maintenance facilities outside Japan and is
remote from air attack.

(d) The presence of a Japanese fleet in Singapore may be induced
by reports that we are contemplating amphibious operations based
on India.

3. The absence of the Japanese battle fleet from the Pacific gives
the Americans a very clear field.

4. It is possible that the Japanese intend to raid our
communications between Calcutta and Ceylon, or in other parts of
the Indian Ocean. Nevertheless, it is not thought that any serious
danger, either to India or to Western Australia, is likely to
develop. Our battleship squadron in Ceylon is well posted. Our
shore-based aircraft are strong. Japan has a total of only four
fleet carriers and eight battleships at present fit for
operations. She is threatened both from the Pacific and from the
Bay of Bengal and she must keep her fleet intact for the later
stages of the war. We, therefore, consider it unlikely that the
new move indicates offensive intentions on the part of Japan.

This, of course, does not preclude the possibility of occasional
offensive sorties.

5. We are taking a number of measures to strengthen our forces in
the Indian Ocean area, particularly in torpedo-bombers and
aircraft carriers. Our cruiser and submarine strength is also
being augmented, and we are considering the provision of further
battleships. Our naval authorities will be in touch with yours on
these matters, but I felt that you should be told of the general
position without further delay and should be made aware of our
thoughts on the subject. It is, of course, most important that the
enemy should not realise the extent of our knowledge, so I must
ask you to regard all this as highly secret.