JFK, Bobbie Kennedy, LBJ, Nixon, NcNamara, Kissinger.   All perpetuated that theory and lied regularly.  The Domino Theory was President Eisenhower's invention, however.  

1954:  "President Dwight D. Eisenhower coins one of the most famous Cold War phrases when he suggests the fall of French Indochina to the communists could create a “domino” effect in Southeast Asia. The so-called “domino theory” dominated U.S. thinking about Vietnam for the next decade."  This was just before Dien Bien Phu's fall.  

The History Channel: 
http://www.history.com/this-day-in-history/eisenhower-gives-famous-domino-theory-speech