Make Mud, Not War

Published on July 5, 2013
By Thomas C. Van Hare

On July 5, 1972, a five-year-long program in Vietnam culminated with a final flight by the 54th Weather Reconnaissance Squadron from Udorn RTAFB, Thailand, known as Operating Location A.  Instead of the typical, traditional role of weather reconnaissance, the 54th carried out a secret mission called, “Operation Popeye”.  Within the squadron, the project was code-named “Motorpool” and it involved a new form of aerial warfare — weather control to impede enemy actions and supply movements.  Cloud seeding with silver iodide was used to bring rain and extend the monsoon season throughout strategic areas within Laos, Cambodia, and Vietnam.

It all worked perfectly well too, until the news media picked up on the story and leaked it to the public.  The resulting outcry caused the shutdown of the program on July 5, 1972 — today in aviation history.


Two RF-4C Phantoms of the 14th TRS and two WC-130As of the 54th WRS in formation near Udorn RTAFB after the completion of the 500th Motorpool mission in 1968.

Operational Profile

Throughout much of the Vietnam War, the 54th Weather Reconnaissance Squadron was based at Andersen AFB, Guam.  To support the “Motorpool” missions under Operation Popeye, small contingents of pilots and crews were regularly rotated for temporary duty to Udorn RTAFB, Thailand, to fly covert missions with two RF-4C Phantom jets brought in from the 14th Tactical Reconnaissance Squadron and three of its own WC-130A Hercules aircraft — and later these were replaced with WC-130B and -E models.


The area of operations spanned from eastern Laos, through the A Shau Valley in South Vietnam, up to the western and south border zones of North Vietnam.  As well, the program expanded to include much of northeastern Cambodia.  With the onset of each monsoon season, the “Motorpool” flights would begin, generally spanning from March to November of each year.  Early experiments had shown that 82 percent of the seeded clouds would produce rain — often extraordinarily heavy rain — and this would severely impact enemy movements across the so-called “Ho Chi Minh Trail” coming southward just west of the borders of Vietnam.  Both the WC-130A Hercules aircraft and the RF-4C Phantoms carried out Motorpool missions, with the Phantoms dropping cloud-seeding silver iodide from regular chaff dispensers.


The cloud seeding kit mounted to the side of a WC-130A Hercules. Photo Credit: USAF

The effects were clear — road capacities were reduced through muddy conditions, landslides, and washouts halted traffic, river crossings were breached, and the enemy supply runs were tied up where they could be more easily targeted by US airstrikes operating along the Trail.  As a result, weather warfare had a great, though rarely mentioned impact on the Vietnam War.  Put simply, it worked — sometimes so well that enemy movements were literally stopped due to heavy rains along targeted border areas.  In all, 1,435 missions were flown in combat over the years, typically with two aircraft based at Udorn and one rotating to Guam for maintenance and normal weather reconnaissance duties there.


End of the Program

Sadly and despite its extraordinary success, the program ended when the New York Times broke the story on July 3, 1972.  Two days later, amidst the public revelations of Operation Popeye, the USAF shut down the operation.  What was colloquially referred to as “Make Mud, Not War”, would result in congressional hearings, widespread international condemnation, and ultimately a new convention on the abolition of weather warfare techniques from the battlefield.  First, in 1974, the Congress and Senate passed a series of resolutions ending “environmental warfare” practices by the US Military.  By 1977, those concepts were expanded globally and rendered into the Environmental Modification Convention, signed in Geneva.


Two RF-4C Phantoms flank a WC-130A of the 54th Weather Reconnaissance Squadron on completion of the 500th Motorpool mission on July 31, 1968.

Weather warfare, widely condemned, was not a crazy concept nor a hopeful but failed venture.  In fact, it was a proven program that brought results.  When the Environmental Modification Convention was passed, it carried clear statements about the dangers of the broad risks that would have evolved from the 54th Weather Reconnaissance Squadron’s mission — cloud seeding was just the beginning, as the convention noted, and it was the world’s duty to assist in “saving mankind from the danger of using new means of warfare”.

As for the 54th Weather Reconnaissance Squadron, it moved on to hurricane tracking missions.  As for the “Motorpool” missions, they were largely forgotten over time.


6 thoughts on “Make Mud, Not War

  1. Frank Doyle says:

    I was an instructor in the RF-4C at Mt. Home AFB, in 1967, 1968 and 1969. During that time I had a “special” student. He was a weather officer. My job was to train him to observe and then take TACAN range and bearing readings. His mission was classified, but now I see that he was part of that Motorpool mission. Find those rain clouds and then seed them.

    Frank Doyle
    RF-4C WSO
    LtCol, USAF, Ret

    1. Vilmar Taylor says:


      I am fanatical about military aviation, particularly the U.S. Air Force and British

      Here in Brazil a company manufactured rockets to launch silver iodide to rain in times of drought in plantations in southern Brazil in the late 80s and 90s

      Here in Brazil a company manufactured rockets to launch silver iodide to rain in times of drought in plantations in southern Brazil in the late 80s and 90s.
      Great mission!!!

  2. Cindy Brewer says:

    Dear Sir,
    My brother in law was Bill Mullins and was a Navigator involved in these missions. He said his Commander would ” bless them out ” for flying into the storms. But they couldn’t reveal their true mission. He only revealed his part shortly before his death in Oct 2019.
    His widow was very excited to see your comment about the ” special student “. She wanted to know if it could have been Bill.
    His dedication and service to our country is a story of a TRUE American Hero. And I am truly honored to respond on behalf of his memory.
    Best regards
    Mrs. Cindy Brewer

  3. John Currie says:

    I flew missions with a CMSGT. Billy the 54th Weather Recon. Squadron from 70-72. Could he have been the same Mullins you refer too above?
    John Currie

  4. Jesse says:

    My dad was part of this unit, he was a crew chief and hydraulics mechanic. I believe he was there in ~1968-69.


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