I hope this will answer some of your question

I also asked my father the same question after 20 yrs since the last time I see him. My father served in the SVNAF and was sent to the re-education camp after the communist invaded South VietNam. If you look at the geographic of VietNam, half the border face in land and other half faced to South Pacific. As a stratigic point in for that time aircraft's and Naval trike range with out supplied and refueling. Yes, if you controll VietNam you would stop the communist invation from China. Yes it is unfortunately that my home land is the last line of defence to stop the tide of communist. But my Dad and the people of VietNam had sacrified for the freedom other Countries freedom. Just look at Cambodia and Lao also had the same fate as us. If the Communist invaded VietNam 50 yrs ago, you think Thailand, Malaysia and Singapore be where they be today. Yes we had died for others to live. I have see things that has haunted me for year during the war as a young child. I hate the communist deeply, but as I grown older, I find hate is not the answer, but to educated myself and hope that some day I can give back to my people as I did swear to VietNam the day I left.