Following for the Prime Minister.

My Circular M.421 of 5th December [1] and M.422. [2] The position
is that we have now received an assurance of armed support from
the United States.

(a) If we find it necessary either to forestall a Japanese landing
in Kra Isthmus or to occupy part of the Isthmus as a counter to
Japanese violation of any other part of Thailand;

(b) If the Japanese attack the Netherlands East Indies and we go
at once to support the latter;

(c) If the Japanese attack us.

2. We have accordingly instructed the Commander in Chief, Far East
[3], that he should take action as he has suggested (see paragraph
2 of my Circular M-406 of 30th November [4]) without reference to
us if either (a) He has good information that a Japanese
expedition is advancing with the apparent intention of landing on
Kra Isthmus, or
(b) The Japanese violate any other part of Thailand.

3. The Commander in Chief, Far East, has also been authorised in
the event of a Japanese attack on the Netherlands East Indies to
put into operation without further reference to us the plans
already agreed with the Netherlands East Indies.