From http://en.wikipedia.org/wiki/Gulf_of_Tonkin_Incident
Later Statements about the incident
Just a few days after the incident, Lyndon Johnson commented privately: "For all I know, our Navy was shooting at whales out there."
In 1981, Herrick and journalist Robert Scheer re-examined Herrick's ship's log and determined that the first 4 August torpedo report which Herrick had maintained had occurred -- the "apparent ambush" -- was in fact unfounded .
Although information obtained well after the fact supported Turner Joy Captain Herrick's statements about the inaccuracy of the later torpedo reports as well as the 1981 Herrick/Scheer conclusion about the inaccuracy of the first, indicating that there was no North Vietnamese attack that night, at the time U.S. authorities and all of the Maddox crew said they were convinced that an attack had taken place. As a result, planes from the carriers Ticonderoga and Constellation were sent to hit North Vietnamese torpedo boat bases and fuel facilities (Operation Pierce Arrow).
Squadron commander James Stockdale was one of the U.S. pilots flying overhead during the second alleged attack. Stockdale wrote in his 1984 book Love and War: " had the best seat in the house to watch that event, and our destroyers were just shooting at phantom targets—there were no PT boats there… There was nothing there but black water and American fire power." Stockdale said his superiors ordered him to keep quiet about this. After he was captured, this knowledge became a heavy burden. He later said he was concerned that his captors would eventually force him to reveal what he knew about this terrible secret.
In 1995, retired Vietnamese General Vo Nguyen Giap, meeting with former Secretary of Defense Robert S. McNamara, categorically denied that Vietnamese gunboats had attacked American destroyers on 4 August, while admitting to the attack on 2 August. A taped conversation of a meeting several weeks after passage of the Gulf of Tonkin Resolution was released in 2001, revealing that McNamara expressed doubts to President Lyndon B. Johnson that the attack had even occurred.
In the Fall of 1999, retired senior CIA engineering executive S. Eugene Poteat wrote that he was asked in early August 1964 to determine if the radar operator's report showed a real torpedo boat attack or an imagined one. He asked for further details on time, weather and surface conditions. No further details were forthcoming. In the end he concluded that there were no torpedo boats on the night in question, and that the White House was interested only in confirmation of an attack, not that there was no such attack.
