Actually, although I was quite young, I specifically remember Dwight Eisenhower, while he was Pres., giving a speech in which he said that we had to go to Vietnam because we needed the bauxite, among other natural resources. Why I remember the bauxite and not the other natural resources he mentioned I have no idea.
http://quickstart.clari.net/qs_se/webnews/wed/ba/Qvietnam-aluminium.Rhds_DSH.html