[1] Prasong started his civil service as a teacher at Ratchaburi boarding school later transferred to military service at the Directorate of Intelligence, Royal Thai Air Force to the rank of a Pilot Officer.

He was a close confidant following Siddhi Savetsila to the Air Force Security Bureau.

From then in 1966, he received a scholarship to study intelligence at the United States Air Force.

[4][5] Prasong was a central figure in the 19 September 2006 Thai military coup that overthrew Thaksin Shinawatra's elected government.

[6] A palace insider and favorite of King Bhumibol Adulyadej, Prasong was later appointed by the junta to the National Legislative Assembly.