Not sure about yor claim that JFK started he Vietnam War. It was actually Pres. Eisenhower who first sent military advisors to SE Asia. Several weeks before his demise, JFK tols the Chiefs of staff in the Pentagon to cancel all military plans for Vietnam as “American boys are not going to do something that that Vietnamese boys ought to be doing”.
As far as Oswald, according to his records in the USMC he couldn’t hit a bull in the ass with a bass fiddle standing right next to it.
Look it up.
Every Marine is first and foremost, a rifleman. If you can’t hit your target, then you don’t become a Marine.