Global InformationOperation Triangle information
| Operation Triangle | |||||||||
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| Part of Laotian Civil War | |||||||||
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| Belligerents | |||||||||
 Kingdom of LaosForces Armées Neutralistes  ThailandSupported by  United States |
 Pathet Lao | ||||||||
| Commanders and leaders | |||||||||
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Souvanna Phouma Kouprasith Abhay Kong Le Leonard S. UngerTony Poe | N/A | ||||||||
| Units involved | |||||||||
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Group Mobile 16 Group Mobile 11 Group Mobile 17 Three ADC battalions Paratroop Battalion 2 Thai artillery battalionThai air support RLAF air support Raven FAC | N/A | ||||||||
Operation Triangle was a military operation of the Laotian Civil War staged from 19—29 July 1964. Although planned by the General Staff of the Royal Lao Army, it was subject to American approval because the RLA depended on the Americans for finances, supplies, and munitions. Operation Triangle was an ambitious undertaking dependent on martial skills unfamiliar to the Lao. It not only called for coordination of infantry, artillery, and tactical air strikes among forces of three different nationalities; as a covert operation, it also had to have plausible deniability.
On 26 June 1964, American ambassador to Laos Leonard Unger was ambivalent about Operation Triangle's chances of success, but felt the opportunity for victory too good to resist. The planning of the military operation may have been local; however, approval to proceed had to come from the White House, where President Lyndon Baines Johnson was monitoring the situation. In any case, it was planned that three Royal Lao Army columns would converge on the intersection of Routes 7 and 13 in Laos, trapping a Lao communist force. With any luck, the highly strategic Plain of Jars would be left exposed to Royal Lao Government occupation.
Despite the RLA's recent losses at Namtha and Lak Sao, the operation was approved. After some weather delays, the operation kicked off on 19 July 1964. One Royalist column left Luang Prabang headed south towards the road intersection at Sala Phou Khoun. Another headed north from Vientiane. The third column moved westward from Muang Soui on the edge of the Plain of Jars.
Stiffened by American forward air controllers, with air power and Thai artillery blasting the way open, the columns closed in on Sala Phou Khoun. On 28 July, two of the columns regrouped just outside the objective. While they coordinated their final attack, Central Intelligence Agency paramilitary officer Tony Poe led an impromptu heliborne assault by Hmong irregulars that occupied the vacant road junction on 29 July.
The Royalist victory was capped when they hauled off considerable military stores abandoned by the fleeing communists, including half a dozen armored cars and eight artillery pieces. However, the route to the Plain of Jars was still blocked by communist forces. As a result, there were hard feelings on part of the RLA regulars, who felt cheated of their triumph. Nor was that the only factor dampening Royalist morale; the Tonkin Gulf Incident of 2 August that officially began the Vietnam War immediately overshadowed Operation Triangle.