The Lacuna Project

lacuna (n.) a gap in a record where something should be

Independent research. Not affiliated with any government, agency, or company.

Exhibit 376

Skunks, Bogies, Silent Hounds, and the Flying Fish: The Gulf of Tonkin Mystery, 2-4 August 1964

Exhibit 376 ยท Agency historical study

Skunks, Bogies, Silent Hounds, and the Flying Fish: The Gulf of Tonkin Mystery, 2-4 August 1964

This was an active effort to make SIGINT fit the claim of what happened during the evening of 4 August in the Gulf of Tonkin.

NSA historian's SIGINT account of 2-4 August 1964. Concludes the 2 August attack on the Maddox occurred and the 4 August attack did not; that about 90 percent of relevant SIGINT was kept out of NSA summaries and the October 1964 report; that the handling was not conspiratorial; and that NSA staff believed an attack had occurred. PDF stamped 'Approved for Release by NSA on 14-03-2005, FOIA Case # 43933'. NSA's own copy URL returned Access Denied to a script; the NSA Archive copy is used.

Source
National Security Agency (Robert J. Hanyok, Cryptologic Quarterly)
Date
Winter 2000/Spring 2001; declassified 1 December 2005
Quoted from
p. 49 (printed page number; scanned PDF page 50)
Grade
Primary record
Document
https://nsarchive2.gwu.edu/NSAEBB/NSAEBB132/relea00012.pdf
Accessed
2026-11-09
Cited by
Findings citing this exhibit
Note
Scanned image PDF; no text layer. Key limits at p. 3 ('not done in a manner that can be construed as conspiratorial') and p. 49 (pressure explanation 'cannot be supported').

Cited by

Finding DEF-2.1
Primary record The NSA historian Robert Hanyok concluded in a study published in 2001 that no attack on U.S. destroyers occurred in the Gulf of Tonkin on the night of 4 August 1964, and his study confirms the 2 August 1964 engagement with the Maddox. He wrote that the mishandling of the signals intelligence was "not done in a manner that can be construed as conspiratorial" and that NSA personnel believed the attack had happened.
Finding DEF-2.2
Primary record Hanyok found that "The withheld information constituted nearly 90 percent of all available SIGINT" and that "only SIGINT that supported the claim that the communists had attacked the two destroyers was given to administration officials."