The National Security Agency has been blocking the release of an article by one of its historians that says intelligence officers falsified documents about a disputed attack that was used to escalate the Vietnam War, a researcher says. Matthew Aid, who asked for the article under the Freedom of Information Act last year, said it appears officers at the NSA made honest mistakes in translating interceptions involving the 1964 Gulf of Tonkin incident. That was a reported North Vietnamese attack on American destroyers that helped lead to then-president Lyndon Johnson's escalation of U.S. involvement in Vietnam. Rather than correct the mistakes, the 2001 article in the NSA's classified Cryptologic Quarterly says midlevel officials decided to falsify documents to cover up the errors, according to Mr. Aid, who is working on a history of the agency, and has talked to a number of current and former government officials about this chapter of American history.