You can contact the National Archives and the National Personnel Records Center to obtain copies of veterans service records. The veteran and next of kin can sometimes request information directly via the Internet with a new Evetrecs service the archives is offering. I've just requested records for a great uncle who is MIA in the Korean War.
A lot of 20th century records were lost in a fire in their repository back in the 1970s, but you should be able to get more information about exactly what is available from the website below. Good luck!