We had Afghan officer cadets at RMA Sandhurst until 1979. I was at staff college with the "class of '79" officer cadet who is now a colonel. Since then we started taking officer cadets again in 2005.
News to me about the American officer cadet. From what I understand it the US system of officer training is quite different from the UK's.
We tended to take mostly Commonwealth officer cadets and a lot of african and middle eastern. Very few Latin American as I recall. In my platoon there was a Thai, an Omani and a Malawian officer cadet, all top blokes and with some interesting stories to tell.
We see a lot of foreign officers on various courses, in fact all the career courses that I have done have had foreign officers on them. Strangely we do not send UK officers on many foreign courses; I cannot help but think we are missing a bit of a trick there.