Following for the Prime Minister.
My immediately preceding telegram M.437. 
1. Since the possibility remains open that the immediate destination of the Japanese convoys is another port in Indo-China there may still be time for warning to Japan by the United States, Dutch and ourselves on the lines contemplated in recent exchanges with President Roosevelt. We have therefore thought it desirable to continue preparations for the delivery of such a warning in order to be in a position to proceed with it if and when the President should give the signal to do so.
2. We have not yet heard whether the President has decided to send the message to the Emperor or not. If he has not yet made up his mind the decision may now be influenced by the news of the sailing of Japanese convoys. We must assume in any event that he may wish to proceed with some form of warning at any moment in which case warnings from ourselves and the Dutch may be required to follow almost immediately afterwards.
3. It would we feel add to the impressiveness of warning (if the President should wish us to proceed with it) if it could be delivered on behalf of all His Majesty's Governments jointly. We very much hope His Majesty's Governments in the Dominions will feel able to concur in this course and identify themselves in this manner with the warning proposed.
4. In view of the urgency of the matter as explained in paragraph (2) we have thought it desirable to prepare and telegraph to His Majesty's Ambassador at Tokyo  a draft note to the Japanese Government conveying a warning in the sense agreed in the recent discussions with the President. The text is contained in my immediately following telegram  and it will be seen that in the hope that the suggestions made in paragraph (3) above will be acceptable it has been drafted as a joint communication. Sir R. Craigie has been instructed to hold this draft note in reserve pending receipt of further instructions and it has been explained to him that the text as well as the form is subject to the concurrence of His Majesty's Governments in the Dominions. The draft has been telegraphed simultaneously to His Majesty's Ambassador at Washington  for the observations of the President. It has also been sent to the Netherlands Government which is entirely in agreement with the line taken by us and is preparing to act similarly.
5. We should be grateful if we could be informed by most immediate telegram whether you concur in the terms of the draft note and in the procedure suggested.  In the circumstances it would be helpful if you would cause your reply to be repeated to His Majesty's Ambassador at Tokyo. 
6. It will be appreciated that in drafting the note we were presented with a special difficulty owing to the desire of the President that the Burma Road should be omitted from the warning (see my telegrams M.433 paragraph (2) and M.434 paragraph (1)).
In the circumstances we have thought it best to relate the warning directly to the concentration of troops in southern Indo-China.
The draft note thus brushes aside the Japanese explanation about north Indo-China and leads logically to the Japanese threat to Thailand  as well of course as the Netherlands East Indies.
This has the merit of being in accordance with immediate realities and the fact that the Philippines are also omitted (in accordance paragraph (3) my telegram M.433) should, we feel, make the absence of mention of the Burma Road less noticeable.