But he said that probably the "most historically significant feature" of the declassified report was the retelling of the 1964 Gulf of Tonkin incident.

That was a reported North Vietnamese attack on American destroyers that helped lead to president Lyndon Johnson's sharp escalation of American forces in Vietnam.

The author of the report "demonstrates that not only is it not true, as (then US) secretary of defense Robert McNamara told Congress, that the evidence of an attack was 'unimpeachable,' but that to the contrary, a review of the classified signals intelligence proves that 'no attack happened that night,'" FAS said in a statement.