The Vietnam war ended when I was still a baby, but I have known numerous people that were in it. My mom had a boyfriend who was really weird about his experiences. He was the type that always talked about the stuff he saw and did, but would never go into details. I can understand wanting to forget the atrocities over there, so why bring it up at all? It seemed as if he was reliving his glory days and his horror all at the same time. He unfortunately died at 41, over 20 years ago, but it would be morbidly interesting to see what would have happened if he was alive today. Have you been in the war? Have you known soldiers that came home and people say they weren't the same? Did they talk about their experiences?
Most of those who came home adjusted quite well. But, as is the case in all wars, it depended on the personality and experiences of each individual.
Anecdotally: My uncle is a combat veteran of Vietnam (USMC). I know he struggled a bit with stress and anxiety after coming back, but later went on to lead a normal life that included a family and a career. That said, all wars leave mental scars on those who fight in them. Some societies, and at different time periods, are better than others at identifying those needing help and getting them said. Vietnam left some pretty big wounds on our veterans and the culture alike.
Before I get into the S.E.Asia "experience" let me talk a little of WWII. I used to have some good encounters with WWII veterans in supermarkets. I would be shopping, they would be shopping, it was a friendly non-threatening atmosphere. Most veterans were open to "light probes", general questions regarding if they were veterans, saw combat. One time I found a WWII era Marine, First Marine Div. Who should walk by but a fellow who happened to have been, on inquiry, Second Marine Div. Wow, me thinks to myself, what are the odds. When I tried to steer my questions, the conversation, to combat and combat experience I could tell the shop suddenly chilled, and both men left. Obviously I struck nerves which were still raw after at least sixty years. As an individual I have spoken to some S.E.Asian veterans. Most causual encounters are light enough, and veterans will speak in generalities. If they saw combat, I have learned, DO NOT probe deep -- if they are going to talk allow them the option to do it at their own pace. I do not want to re-injure any old scabbed-over wounds.