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.

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.

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.

The Laotian Civil War came about as the United States moved in to take the place of the French administrators departing Laos as a result of the 1954 Geneva Conference.

Faced with an escalating communist insurgency backed by the Democratic Republic of Vietnam, the Royal Lao Government defended itself at the battles of Luang Namtha and Lak Sao, only to lose badly.

Although a limited military operation aimed at a stranded pocket of enemy troops, he hoped it would be the preliminary success needed to recapture the Plain of Jars.

[3] On 13 June, the RLAF flew 17 sorties against Pathet Lao artillery and antiaircraft guns on Phou Kout Mountain menacing Neutralist positions near Muang Soui.

Royal Lao Government units were tasked to converge on Sala Phou Khoun at the 7/13 junction from their starting points at Vientiane, Luang Prabang, and Muang Soui.

However, by late June it was doubted that operational security could keep the RLG plans secret; if the Pathet Lao were tipped off, they might reinforce with North Vietnamese regulars.

[6] Ambassador Unger noted that success was chancy, and that the overt American action involved might call attention to the U.S. violation of the International Agreement on the Neutrality of Laos.

Despite this wishy-washy estimate, and the RLG failure in the recent Battles of Lak Sao and Luang Namtha, the Embassy favored Operation Triangle.

It called for aerial reconnaissance by Air America, the daily delivery of 23 tons of supplies to the columns, and napalm for arming the RLAF's T-28 Trojans.

[4] Despite this early promise, from 21 July onwards GM 16 slowed its march westward on the poorly constructed Route 7 toward Sala Phou Khoun, fearing land mines.

On 22 July, GM 11 from Luang Prabang departed its intermediate objective at Phou Chia accompanied by an American combat controller and a U.S. Army adviser.

Relaying instructions through an airborne radio link and using large bamboo arrows as target designators, they had the RLAF's Lao and Thai pilots clearing the road ahead of them with bombs.

The following day, three ADC companies of irregulars led by CIA case officer Tony Poe were heli-lifted into Sala Phou Khoun by Air America.

The U.S. proposal to bomb the mountain with napalm was scotched because British ambassador Donald Hopson objected to its use, and the paratroopers were unable to capture the heights in four attempts.

[4] Captured booty from Sala Phou Khoun included six armored cars, four Soviet 85mm field guns, four 105 mm howitzers, 12 trucks, and tons of munitions.

At any rate, timing favored obscurity, as the Tonkin Gulf Incident of 2 August pulled America into the Vietnam War even as Operation Triangle was ending.