After the administration of Thailand had changed from the absolute Monarchy in 1932. The military government of Thailand enforced Law and Order of security system to protected the advantage of civilian and military. At the beginning, between the second World War, The Act of 1940 about the protection for the secret of government service was promulgated. The military government modified that Act for profit the military base and the important public.
When the Cold War was begun and Communist country related to Southeast Asia. The military government was apprehensive of the threat of Communist countries. Moreover the politics in Bangkok was confused.
By The Manhattan rebel in 1951, Field Marshal Plaek Pibulsongkram, the prime minister of Thailand, wanted to be relationship with other militant countries, to be balanced his power. So Thailand was led to USA alliance to against Communist countries. The first participant was the Manila Pact in 8 September 1954, the cooperation with USA and 7 countries; United Kingdom, France, Australia, New Zealand, Pakistan, The Philippines, and Thailand.
Nevertheless, the Thai government was realized about the important of intelligence service. Field Marshal Plaek sat up the first of the intelligent agency in 1 January 1954. It was called Department of National Intelligent, to be stationed in intelligence service country, espionage, and protective security.
The consequence from Manila Pact, Thailand became the alliance of Southeast Asia Treaty Organization (SEATO) in 19 February 1955. Their objective was to protect the alliance from the related of Communist countries, led by China. Therefore the Thai government declared the security regulation for controlling about the operation and document from the military and civil officer who worked with the partnership. The first regulation for protective security was in 14 July 1956, The Ministry Rule for protective the secret government service, 1956. Department of National Intelligent was the only civil unit to take responsibility that rule for government. From this, the slogan“ need to know” became to the way of all officer.
From December 1959, Department of National Intelligent was changed to Department of Central Intelligent. At the same time, Ministry of Defense asked for the cabinet to adjust The Ministry Rule for protective the secret government service, 1956 and approved in 23 November 1967. The new rule called The Rule of National Protective Security 1968, the important factor of the adjustment was divided the responsibility security unit for civilian and for military. However the new rule was passed by the cabinet but not to be announced in the government gazette.
Until 20 May 1969, Ministry of Defense asked for eliminate The Rule of National Protective Security 1968. The eliminate passed for five years. The cabinet approved of the new role in 18 December 1974, was called The Rule of National Protective Security 1974, and be announced in the government gazette in 16 February 1975. The detail of rule was the same as the primary rule but appointed The Committee for the Coordination of the Rule of National Protective Security. Afterward Telecommunication was necessary in the way of live but not the rule for usability. So The Rule of National Protective Security for Telecommunication 1982 was announced and the 2 protective security units were responded for this rule.
Because of the change of public law at the time, the cabinet approve to modify the rule for the administration. The Rule of National Protective Security 1974 was the one. The change of that rule began in 1995
Until Official Information Act, B.E. 2540 (1997) was promulgate. Because of the no.16 regulation of this Act, The Rule of National Protective Security 1974 was changed. Official Information Act, B.E. 2540 ordain to the rule for information protection only. So The Rule of the protection for secret information 2001 was announced and then The Rule of National Protective Security 1974 in the chapter of the defensive measures defend for the official document and The Rule of National Protective Security for Telecommunication 1982 were canceled because the 2 rules were out of date.
Even though the change of The Rule of National Protective Security 1974 was over and done in 2009. The new rule consisted of 2 regulations, the discipline was the way of system and the practice was the way of acting. For responsibility unit was be changed to 3 units that for the police, the military, and the civilian, as The National Intelligent Agency.