Well there was the stuff about mixed messages from the government

maybe the pm was quite keen on american help, but the military were not quite so keen and the americans were not too keen to offer if the entire government was not keen to accept. After all having american service personal wandering around the place might complicate their coup plans; there's always the risk you might shoot one during the coup and would right piss off the americans.

but then I am assuming that there were mixed messages from thailand, the military are planning a coup and that they give a shit what americans think if they shoot one of theirs. which is rather a lot of assuming