From what I recall from crew briefings during the Vietnam war, we had three kinds of chemical irritant for use in rescuing downed crew in enemy territory: DL, CN, and CS. DL was conventional tear gas, CN was a 'nausea' agent, and CS was 'not used because it was too dangerous to the downed crewman'.
Which is why the idea of a 'personal CS spray' cannister makes me go "huh?"