British Ambassador [2] saw Sumner Welles [3] today in continuation
of our joint discussion with him (Sumner Welles) on 2nd August.

In terms which British Ambassador describes 'conversational'
Sumner Welles' remarks were of first class importance and were
very considerably in advance of anything that he has said before.

Sumner Welles said he was pressing the Japanese Ambassador [4] for
a reply regarding the proposal (effectiveness of which I do not
rate highly) for 'neutralizing' Thailand.

British Ambassador enquired what it was proposed to do if the
neutralizing' proposal failed.

Sumner Welles said that he was today asking Counsellor of Japanese
Embassy here to call on him. This particular Japanese official is
just about to return to Tokyo to report on position in United
States. [5] Sumner Welles said he proposed to tell Japanese
Counsellor that 'if the Japanese pursued their projected plan in
Thailand and continued on towards Netherlands East Indies or
Singapore and northward (which Halifax assumed meant Burma) it was
quite inevitable that, not necessarily tomorrow or next month but
sooner or later, Japanese Government would find themselves
involved in war with the United States.' [6]

Sumner Welles then went on to speak of authority given in June to
American Ambassador at Tokyo [7] to Speak, at his discretion, in
strong terms to Japanese Minister for Foreign Affairs [8]
(referred to in my telegrams 584 [9] and 589 [10]). He described
potential statement (which has not, as assumed in P.M.'s [11]
telegram 85[12], been made) as defining 'attitude of the United
States in the event of Japanese attempt to cut the British
lifeline by attack on the Netherlands East Indies and Singapore'
and said, 'If the Japanese went for N.E.I. he had no doubt that
that would mean war with the British Empire and that in such an
event it would inevitably mean that the United States would be
involved.' Sumner Welles went on to say that Japanese attack on
N.E.I. or Singapore would plainly show the Japanese determination
to establish a hegemony in that vital area which the United States
could not tolerate. Hull [13] is now back at State Department
after a month's illness and was to see the Thai Minister [14] this
morning to say to him that if the Thais stood up to the Japanese,
as he hoped they would, the United States would give them all the
help in their power, as they had been giving help to China.

CASEY