DESOTO patrol


DESOTO patrols
were patrols conducted by U.S. Navy destroyers equipped with a mobile "van" of signals-intelligence equipment used for intelligence collection in hostile waters.
The became the namesake for these patrols. De Haven performed the first patrol off the coast of China in April 1962. The carried out the first patrol to target North Vietnam in the Gulf of Tonkin in December 1962.
These patrols were initially a response to the Chinese Communists' unexpected re-definition 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.
These types of patrols had previously been conducted off the coasts of the Soviet Union, China, and North Korea, but are widely recognized for their role in the Vietnam War. 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.
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 provided destroyers taking part in the DESOTO patrols off Vietnam with air support.
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.

Patrols and SIGADs

The naval Direct Support Units based out of the U.S. Naval Communication Station, Philippines, in San Miguel, Philippines 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.

Declassified SIGADs

The following table lists the patrols that have been declassified.
Patrol NumberPatrol DatesPrimary Patrol ShipSIGAD
114-20 April 1962USN-467?
9December 1964USN-467?
?25 February - 12 March 1964USN-467Y
1828 July - 23 August 1964USN-467N
1914-21 September 1964USN-467P
201-15 October 1964USN-467R-1
2115 October - 14 November 1964USS MortonUSN-467R-2
228-14 November 1964USS Richard S. EdwardsUSN-467S
2314 November - 27 December 1964USS Richard S. EdwardsUSN-467R-3
248 - 14 February 1965USN-467D
2515 February - 19 March 1965USN-467D
2619 March - 21 April 1965USN-27/USS BuchananUSN-467D

Gulf of Tonkin Incident

SIGAD USN-467N specifically designates the DSU aboard during the patrol involved with the Gulf of Tonkin incident. This patrol was 18th DESOTO type patrol conducted since 1962. On August 2, 1964, the destroyer Maddox, engaged three North Vietnamese Navy torpedo boats of the 135th Torpedo Squadron. A sea battle resulted, in which Maddox expended over two hundred and eighty and shells, and in which four USN F-8 Crusader jet fighter bombers strafed the torpedo boats. One US aircraft was damaged, one 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.

Post Gulf of Tonkin Engagement

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