I can tell you it is not generally culturally accepted in the U.S.
I have worked with the South Korean Military in the past, and I can tell you that they consider that type of corrective action (and then some) acceptable.
Having been an instructor in the Army and attended many high speed type Special Ops schools and training...I have never been slapped nor found a reason to slap a student. Give honest constructive criticism yes....but to call them stupid, slap them, berate them ....is never called for. Sometimes the truth hurts...but having someone give you warm and fuzzies just to be nice and polite may get you killed by making you think you are better than you really are...but that still doesn't mean you have to abuse someone!