143 Department of External Affairs to Mr R. G. Casey, Minister to the United States

Cablegram 190 28 September 1940,

MOST SECRET

Last paragraph your telegram 240. [1] Following arguments have been suggested by Defence Committee with approval of War Cabinet.

(A) Only sure way to defeat Japan and protect U.S.A. interests in the Far East is by naval forces in Far East. These require chain of bases in South-western Pacific to give fleet necessary mobility.

(B) Such bases would allow the U.S.A. to use bases in the Philippines for offensive action if attacked by Japan.

(C) Such bases would materially assist in maintaining the status quo in the Dutch East Indies because of the potential threat from the U.S.A. Fleet.

(D) These bases would enable the U.S.A. fleet to assist Australia and New Zealand against any attack by Japan, thus assisting in preventing Japan from obtaining a hegemony of the Western Pacific.

(E) These bases would form an outer screen for the U.S.A. fleet in the defence of U.S.A. trade and territory.

For your own information Defence Committee concluded that it would be most advantageous to United States to have use of bases in South-Western Pacific if they wish to undertake offensive action against Japan. Singapore and Manila most important as final operational bases for this purpose but in event of successful Japanese attack on Dutch East Indies Darwin and Port Moresby would be of enhanced importance. Suitable bases for offensive action against Japan exist or are being developed in Suva, Port Moresby and Darwin and could be used for this purpose at least for cruisers and light forces. Other suitable sites such as Suva Bay (Fiji), New Guinea and Bynoe Harbour (near Darwin) might be leased if political considerations allowed.

Question primarily naval but air and army units would be necessary for security of bases and adequate shore based aircraft would be required to provide distant sea reconnaissance supported by striking force.

1 Document 99. Casey repeated his request for information on 24 September. See cablegram 280 on file AA:A981, Pacific 8, i.

[AA:A981, PACIFIC 11, i]