Remember the second Gulf of Tonkin incident?'
It was originally claimed by the National Security Agency that the second Tonkin Gulf incident occurred on August 4, 1964, as another sea battle, but instead may have involved "Tonkin Ghosts"[6] (false radar images) and not actual NVN torpedo boat attacks.
The outcome of these two incidents was the passage by Congress of the Gulf of Tonkin Resolution, which granted President Lyndon B. Johnson the authority to assist any Southeast Asian country whose government was considered to be jeopardized by "communist aggression." The resolution served as Johnson's legal justification for deploying U.S. conventional forces and the commencement of open warfare against North Vietnam.
In 2005, an internal National Security Agency historical study was declassified; it concluded[7] that the Maddox had engaged the North Vietnamese Navy on August 2, but that there were no North Vietnamese naval vessels present during the incident of August 4.
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According to Raymond McGovern, a retired CIA officer, CIA analyst from 1963 to 1990, and in the 1980s chairman of the National Intelligence Estimates, the CIA, "not to mention President Lyndon Johnson, Defense Secretary Robert McNamara and National Security Adviser McGeorge Bundy all knew full well that the evidence of any armed attack on the evening of Aug. 4, 1964, the so-called second Tonkin Gulf incident, was highly dubious....During the summer of 1964, President Johnson and the Joint Chiefs of Staff were eager to widen the war in Vietnam. They stepped up sabotage and hit-and-run attacks on the coast of North Vietnam". The Maddox, carrying electronic spying gear, was to collect signals intelligence from the North Vietnamese coast, and the coastal attacks were seen as a helpful way to get the North Vietnamese to turn on their coastal radars. For this purpose, it was authorized to approach the coast as close as eight miles and the offshore islands as close as four; the latter had already been subjected to shelling from the sea.[31]
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In October, 2005 the New York Times reported that Robert J. Hanyok, a historian for the U.S. National Security Agency, concluded that NSA deliberately distorted intelligence reports passed to policy-makers regarding the August 4, 1964 incident. He concluded the motive was not political, but rather to cover up honest intelligence errors.[40]
http://en.wikipedia.org/wiki/Gulf_of_Tonkin_incident#Second_Alleged_Attack
That was 50 years ago.