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DESOTO patrol

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DESOTO patrols (DeHaven Special Operations off TsingtaO)[1] were patrols conducted by U.S. Navy destroyers equipped with a mobile "van" of signals-intelligence equipment used for intelligence collection in hostile waters.[2] The USS De Haven became the namesake for these patrols.[3] De Haven performed the first patrol off the coast of China in April 1962. The USS Agerholm carried out the first patrol to target North Vietnam in the Gulf of Tonkin in December 1962.[3]

USS De Haven

These patrols were initially a response to the Chinese Communists' unexpected re-definition[when?] of their territorial waters to include all waters shoreward from lines drawn tangentially to, and between, twelve-mile circles drawn around their offshore islands. Such a declaration represented a huge expansion of their claims. This inhibited the lawful navigation of international waters as defined by US interests and increased the likelihood and frequency of formal diplomatic "serious warnings" issued by Beijing when any Seventh Fleet units navigated through these areas. This became a situation to which Commander Seventh Fleet felt compelled to respond.[1]

These types of patrols had previously been conducted off the coasts of the Soviet Union, China, and North Korea, but are perhaps of greatest significance for their role in the Vietnam War.[1] There were three components to the purpose of these patrols. First, they would establish and maintain the presence of the U.S. Seventh Fleet in the international waters off the China coast and later the Vietnamese coast. Second, they would serve as a minor Cold War irritant to the Chinese Communists. Third, they would collect as much intelligence as possible during the patrols.[3]

Tactically, the patrols off Vietnam aimed to intercept North Vietnamese Army intelligence and to relay it to South Vietnamese Army forces. With the intercepted communications, the South Vietnamese were able to more effectively coordinate their raids. The aircraft carrier USS Ticonderoga provided destroyers taking part in the DESOTO patrols off Vietnam with air support.[1]

The DESOTO patrols off Vietnam from 1963 onwards formed part of a larger scheme known as Operation 34A. Run by the Department of Defense at the time, Operation 34A, or "OPLAN 34Alpha" was a top-secret program consisting primarily of covert actions against the North Vietnamese.[citation needed]

Patrols and SIGADs[edit]

The naval Direct Support Units (DSUs) based out of the U.S. Naval Communication Station, Philippines, in San Miguel, Philippines (SIGAD USN-27)[4] used the SIGAD USN-467 as a generic designator for their missions. Each specific patrol received a letter suffix for its duration. The subsequent mission would receive the next letter in an alphabetic sequence.[5]

Declassified SIGADs[edit]

The following table lists the patrols that have been declassified.[3][6][7]

DESOTO patrol mission map off Vietnam.
Patrol Number Patrol Dates Primary Patrol Ship SIGAD
1 14–20 April 1962 USS De Haven USN-467?
9 December 1964 USS Agerholm USN-467?
? 25 February - 12 March 1964 USS John R. Craig USN-467Y
18 28 July - 23 August 1964 USS Maddox USN-467N
19 14–21 September 1964 USS Morton USN-467P
20 1–15 October 1964 USS Richard S. Edwards USN-467R-1
21 15 October - 14 November 1964 USS Morton USN-467R-2
22 8–14 November 1964 USS Richard S. Edwards USN-467S
23 14 November - 27 December 1964 USS Richard S. Edwards USN-467R-3
24 8–14 February 1965 USS Towers USN-467D
25 15 February - 19 March 1965 USS Buchanan USN-467D
26 19 March - 21 April 1965 USN-27/USS Buchanan USN-467D

Gulf of Tonkin Incident[edit]

USS Maddox

SIGAD USN-467N specifically designates the DSU aboard USS Maddox during the patrol involved with the Gulf of Tonkin incident.[5][8] This patrol was 18th DESOTO type patrol (each with a Naval Security Group detachment embarked) conducted since 1962.[9] On August 2, 1964, the destroyer Maddox, engaged three North Vietnamese Navy torpedo boats of the 135th Torpedo Squadron.[10] A sea battle resulted, in which Maddox expended over two hundred and eighty 3-inch (76 mm) and 5-inch (127 mm) shells, and in which four USN F-8 Crusader jet fighter bombers strafed the torpedo boats. One US aircraft was damaged, one 14.5-millimeter (0.57 in) round hit the destroyer, three North Vietnamese torpedo boats were damaged, and four North Vietnamese sailors were killed and six were wounded; there were no U.S. casualties.[11]

Post Gulf of Tonkin Engagement[edit]

USS Morton

Even after the Gulf of Tonkin incident, the DESOTO patrols continued. On 11 September 1964 the Director of the Naval Security Group, Pacific (DIRNAVSECGRUPAC) informed the Director of the NSA (DIRNSA) of plans for an intercept team, SIGAD USN-467P, to be aboard USS Morton. The patrol was conducted by USS Morton and USS Richard S. Edwards approximately one month after the Gulf of Tonkin incident.[12] During this patrol Morton fired upon five fast closing targets, but was unable to confirm the targets visually.[12] Based on radar surveillance the patrol claimed hits on three of the targets.[12]

See also[edit]


  1. ^ a b c d James W. Montgomery. "The First DESOTO Patrol". Retrieved 2010-05-04.
  2. ^ National Security Agency (30 November 2005). "Gulf of Tonkin". declassified materials, 2005 and 2006. Archived from the original on 2007-09-11. Retrieved 2007-10-02.
  3. ^ a b c d "The Gulf of Tonkin Incident" (PDF). Feb 1975. Archived from the original (PDF) on 2013-09-18. Retrieved 6 Jul 2013.
  4. ^ "Spartans in Darkness:American SIGINT and the Indochina war, 1945-1975" (PDF). 24 February 1998. pp. 498–500. Archived from the original (PDF) on 2013-09-18. Retrieved 11 June 2013.
  5. ^ a b William Gerhard (June 1969). In the Shadow of War (To the Gulf of Tonkin), Cryptologic History Series, Southeast Asia. National Security Agency. p. 51.
  6. ^ "Operational History" (PDF). 26 May 1965. p. 12. Archived from the original (PDF) on 18 September 2013. Retrieved 6 July 2013.
  7. ^ "Operational History" (PDF). 26 May 1965. p. 2. Archived from the original (PDF) on 18 September 2013. Retrieved 6 July 2013.
  8. ^ "Skunks, Bogies, Silent Hounds, and the Flying Fish: The Gulf of Tonkin Mystery, 2-4 August 1964" (PDF). 24 February 1996. p. 50. Archived from the original (PDF) on October 11, 2013. Retrieved 11 June 2013.
  9. ^ "Operational History" (PDF). 26 May 1965. p. 10. Archived from the original (PDF) on 18 September 2013. Retrieved 6 July 2013.
  10. ^ Moïse 1996, p. 78.
  11. ^ Moïse 1996, pp. 78, 82, 92.
  12. ^ a b c "REVIEW OF THE DESOTO PATROL: 16-20 September 1964" (PDF). 14 Jan 1965. p. 5. Archived from the original (PDF) on 2013-09-18. Retrieved 6 Jul 2013.

Works cited[edit]

  • Moïse, Edwin E. (1996). Tonkin Gulf and the escalation of the Vietnam War. Chapel Hill: University of North Carolina Press. ISBN 0-8078-2300-7.