WASHINGTON - The National Security Agency has released hundreds of pages of long-secret documents on the 1964 Gulf of Tonkin incident, which played a critical role in significantly expanding the American commitment to the Vietnam War.
The material, posted on the Internet overnight Wednesday, included one of the largest collections of secret intercepted communications ever made available. The most provocative document is a 2001 article in which an agency historian argued that the agency's intelligence officers "deliberately skewed" the evidence passed on to policy makers and the public to falsely suggest that North Vietnamese ships had attacked American destroyers on Aug. 4, 1964.
Based on the assertion that such an attack had occurred, President Lyndon B. Johnson ordered airstrikes on North Vietnam and Congress passed a broad resolution authorizing military action.
The historian, Robert J. Hanyok, wrote the article in an internal publication and it was classified top secret despite the fact that it dealt with events in 1964. Word of Mr. Hanyok's findings leaked to historians outside the agency, who requested the article under the Freedom of Information Act in 2003.
Some intelligence officials said they believed the article's release was delayed because the agency was wary of comparisons between the roles of flawed intelligence in the Vietnam War and in the war in Iraq. Mr. Hanyok declined to comment on Wednesday. But Don Weber, an agency spokesman, denied that any political consideration was involved.
"There was never a decision not to release the history" written by Mr. Hanyok, Mr. Weber said. On the contrary, he said, the release was delayed because the agency wanted to make public the raw material Mr. Hanyok used for his research.
"The goal here is to allow people to wade through all that information and draw their own conclusions," he said.
Thomas S. Blanton, director of the National Security Archive at George Washington University, called the release of the document "terrific," noting that the eavesdropping material known as signals intelligence, or sigint, is the most secret information the government has.
"N.S.A. may be the most close-mouthed of all U.S. government agencies," said Mr. Blanton, whose organization has published on the Web many collections of previously secret documents. "The release of such a large amount of sigint is unprecedented."
In his 2001 article, an elaborate piece of detective work, Mr. Hanyok wrote that 90 percent of the intercepts of North Vietnamese communications relevant to the supposed Aug. 4, 1964, attack were omitted from the major agency documents going to policy makers.
"The overwhelming body of reports, if used, would have told the story that no attack had happened," he wrote. "So a conscious effort ensued to demonstrate that an attack occurred."
Edwin E. Moïse, a historian at Clemson University who wrote a book on the Gulf of Tonkin incident, said the agency did the right thing in making public Mr. Hanyok's damning case. "A lot of people at the agency haven't been happy that communications intelligence was used to support a wrong conclusion," he said.
Agency employees worked late Wednesday to meet a self-imposed end-of-November deadline, posting the intercepts, oral history interviews with retired agency officials and internal reports on the agency's Web site at www.nsa.gov/vietnam/index.cfm.
The agency, based at Fort Meade, Md., intercepts foreign communications, like phone calls, e-mail messages and faxes, and is charged with protecting the security of American government communications. With more than 30,000 employees, including codebreakers, computer experts and linguists, it is the largest American intelligence agency.
Its Center for Cryptologic History, where Mr. Hanyok works, has published studies of the role of signals intelligence in many major episodes in American history, including Pearl Harbor, the Korean War and the Cuban missile crisis. Among its most extensive projects was publishing and annotating Soviet diplomatic messages from the 1940's decoded by agency codebreakers in a program called Venona.
© 2005 New York Times