An NYT story reports the U.S. National Security Agency is sitting on a historical study completed in 2001 that found some of its agents "deliberately distorted critical intelligence to cover up their mistakes" in the 1964 Tonkin Gulf incident that triggered the Vietnam War.

An excerpt:

The historian's conclusion is the first serious accusation that communications intercepted by the N.S.A., the secretive eavesdropping and code-breaking agency, were falsified so that they made it look as if North Vietnam had attacked American destroyers on Aug. 4, 1964, two days after a previous clash. President Lyndon B. Johnson cited the supposed attack to persuade Congress to authorize broad military action in Vietnam, but most historians have concluded in recent years that there was no second attack.

The N.S.A. historian, Robert J. Hanyok, found a pattern of translation mistakes that went uncorrected, altered intercept times and selective citation of intelligence that persuaded him that midlevel agency officers had deliberately skewed the evidence.

Mr. Hanyok concluded that they had done it not out of any political motive but to cover up earlier errors, and that top N.S.A. and defense officials and Johnson neither knew about nor condoned the deception.

Mr. Hanyok's findings were published nearly five years ago in a classified in-house journal, and starting in 2002 he and other government historians argued that it should be made public. But their effort was rebuffed by higher-level agency policymakers, who by the next year were fearful that it might prompt uncomfortable comparisons with the flawed intelligence used to justify the war in Iraq, according to an intelligence official familiar with some internal discussions of the matter.

Matthew M. Aid, an independent historian who has discussed Mr. Hanyok's Tonkin Gulf research with current and former N.S.A. and C.I.A. officials who have read it, said he had decided to speak publicly about the findings because he believed they should have been released long ago.

"This material is relevant to debates we as Americans are having about the war in Iraq and intelligence reform," said Mr. Aid, who is writing a history of the N.S.A. "To keep it classified simply because it might embarrass the agency is wrong."

This is worth noting too:

Many historians believe that even without the Tonkin Gulf episode, Johnson might have found a reason to escalate military action against North Vietnam. They note that Johnson apparently had his own doubts about the Aug. 4 attack and that a few days later told George W. Ball, the under secretary of state, "Hell, those dumb, stupid sailors were just shooting at flying fish!"

But Robert S. McNamara, who as defense secretary played a central role in the Tonkin Gulf affair, said in an interview last week that he believed the intelligence reports had played a decisive role in the war's expansion.

"I think it's wrong to believe that Johnson wanted war," Mr. McNamara said. "But we thought we had evidence that North Vietnam was escalating."

Mr. McNamara, 89, said he had never been told that the intelligence might have been altered to shore up the scant evidence of a North Vietnamese attack.