Graham Greene was a journalist in Vietnam during 1951-1954. His 1955 novel The Quiet American depicts the US as plotting with Trình Minh Thế's Caodaiist faction to bomb a military parade in Saigon, so that the communists could be falsely blamed.
This tale is apparently based on actual bombings that were conducted by Trình Minh Thế's faction in Saigon. In
Jammes, J. (2011). La répression comme fonction sociale complexe. Etat, religion et répression en Asie-Chine, Corée, Japon, Vietnam (XIII-XXI ième siècles).
the historian of Caodaiism Jérémy Jammes asserts that Trình Minh Thế's faction "stood out for its terroristic actions in Saigon during 1951-1953." Is there any evidence to suggest US culpability in any of those actions?