The National Security Agency had some 10,000 cryptographers and other intelligence gathering and translation personnel in Southeast Asia in 1964, yet NSA historian Robert Hanyok wrote in the agency's history that two key points in the war had intelligence problems.

The first was the 1964 Gulf of Tonkin incident, in which a purported second North Vietnamese attack on U.S. forces triggered a major escalation in the war, The Christian Science Monitor reported. However, it later became clear the second attack never occurred as a radio intercept had been mistranslated, the report said.

The second incident was the start of the Tet offensive Jan. 31, 1968. U.S. intelligence picked up communications talking of an attack on Saigon and other cities on "N-day," which never materialized, the report said.

Hanyok said "critical information was mishandled, misinterpreted, lost, or ignored" in both major incidents.