As an Army officer (1980-2000) we were keenly aware of PTSD
and trained on how to detect it by 1984. In 1986, I had a platoon sergeant have a "flashback" during an artillery live fire exercise when I was in 2nd ID on the DMZ in Korea. He was rapidly medevaced stateside for teatment.
https://www.publichealth.va.gov/exposures/publications/agent-orange/agent-orange-summer-2015/nvvls.asp