General impression particularly in Netherlands East Indies, Singapore and Bangkok that the Japanese mean some sort of mischief and that only very strong line by the United States will restrain them.
Casey  should be instructed to concert with Halifax  strongest representations to Roosevelt. I believe that if Japan were told exactly where the chalk line was, she would hesitate to engage in a venture in which her navy might be defeated and her whole status consequently destroyed.
You might consider whether Latham  might be accredited to Thailand to go there and use influence against the surrender to Japanese influence.
The Prince  who is leading Thailand Mission to Japanese arbitrator is friendly but may be afraid of Japan.