How the U.S. Air Force Spied on French Nuke Blasts
Special tanker planes snooped on Pacific tests
by JOSEPH TREVITHICK
During the early years of the Cold War, the United States had a problem.
The U.S. had quickly lost its monopoly on nuclear weapons. The Pentagon was most concerned about Soviet and Chinese weapons, but France was also building a nuclear bomb.
France was — and is — a U.S. ally. But still, it was reason enough for America to send in its spy planes.
In the 1960s, two specially modified KC-135R Stratotankers joined the U.S. Air Force’s 55th Strategic Reconnaissance Wing. The aircraft had special gear to covertly gather data on French detonations in the South Pacific.
“France conducted its nuclear tests … on the Mururoa Atoll in the Tuamotu Archipelago of French Polynesia,” an official Air Force history stated. “Nearly all French nuclear devices were detonated from balloons, but an occasional one was dropped from aircraft.”
The National Security Archive at George Washington University obtained this historical review and other documents via the Freedom of Information Act.
It’s a revealing look at how allies spy … on allies.
American agents had kept an eye on French nuclear aspirations from as early as 1946. With the Cold War underway, Washington worried that the French nuclear program might fall into the wrong hands.
“A reliable source reports that there has been a rumor circulating to the effect that French scientists have the formula and techniques concerning atomic explosives,” Army Lt. Col. S.M. Skinner, a member of the Strategic Services Unit, wrote that year in a memo to the Manhattan Project’s Foreign Intelligence Section.
“They are now willing to sell this information,” Skinner added.
The Strategic Services Unit spun off from the Office of Strategic Services after World War II. The group existed briefly before being absorbed into the new Central Intelligence Agency.
“[Frédéric] Joliot-Curie inspired suspicion because of his communist politics,” Jeffery Richelson, a senior fellow at the National Security Archive, wrote in his book Spying on the Bomb.
Joliot-Curie—among the academics named in Skinner’s note—was a prominent physicist, a member of France’s nuclear research team … and a former member of the Communist National Front resistance group against the Nazis.
On top of that, France had an active Communist party and powerful left-leaning politicians. American officials often butted heads with the country’s more centrist leaders, as well.
And regardless, “any nation’s possession of nuclear weapons and its strategic doctrine governing their use could have an impact on the balance of power in a region, as well as the prospects for crisis resolution and deterrence,” Richelson wrote in an email to War Is Boring.
So when the French set off their first first nuclear bomb in Algeria 14 years later, the CIA was well aware of what was going on. When Algiers forced Paris to move its testing to the Pacific, American spooks followed.
But these new, remote test facilities were much more difficult to monitor.
Three years after Paris’ first atomic bomb exploded, the U.S. Intelligence Board had “decided against … overflights because of State Department concern about potential political difficulties with France in the event the mission was discovered,” Gregory Pedlow and Donald Welzenbach wrote in the CIA’s official history of the U-2 spy plane.
The Intelligence Board included the director of national intelligence, the CIA, National Security Agency, the Defense Intelligence Agency and the State Department. The committee reviewed all of Washington’s spying activities, and signed off on final reports to the White House.
The CIA used a special version of the U-2—which could take off from and land on a U.S. Navy aircraft carrier—to reach these Pacific proving grounds. But Operation Fish Hawk was painfully complex.
Instead, the Air Force’s top-secret nuclear sniffing tankers could fly from Hawaii and back without necessarily arousing attention. Regular KC-135s refueled the aerial spies during the missions—nicknamed Burning Light—and the whole affair would easily look like a training exercise.
But it’s debatable whether this succeeded in keeping the flights’ true nature actually secret. “I suspect they would assume the U.S. was interested in obtaining intelligence on their program,” Richelson wrote.
In any case, after getting alerts of impending French tests from the NSA, the 55th would fly these covert spy planes near Mururoa, according to another Air Force history.
The crews could measure the size of the blasts by recording their electromagnetic pulses, and take photographs of the explosions’ mushroom clouds.
In addition, the spies could remove their specialized sensors with relatively little effort. This allowed the secretive Air Force Technical Applications Center—which still deals in nuclear intelligence today—to keep a tight lid on the activities.
“AFTAC personnel installed the sensor systems prior to each NUDINT [nuclear detonation intelligence] sortie,” the historical review added. The same teams then “removed them upon completion of the mission.”
The setup meant the Air Force’s Strategic Air Command could quickly convert the planes for more mundane flights, or send them on other spy missions. For instance, when they weren’t scanning nuclear plumes in the Pacific, one of the two aircraft was scooping up radio chatter near Cuba.
“The operation required considerable personnel, money and materiel,” the historical review added. “In the June 1971 project, for example, the 55th … deployed seven KC-135A tankers, eight tanker crews and four crews to fly the two KC-135Rs from Hickam [Air Force Base].”
In total, more than 200 people participated in the two Burning Light missions that month. Between 1968 and 1972, the spying tankers made 30 passes over the French testing area.
The overflights also made good practice. At the time of the Burning Light missions, Washington and Moscow were observing a voluntary moratorium on atomic tests.
“Not only did these sorties gather information on France’s current testing, but they also provided an opportunity to perfect equipment and collecting techniques … if SAC was ever required to monitor a nuclear blast,” the Air Force reported.
The next year, the Air Force Special Weapon Center converted two aircraft specifically for nuclear spying. These new NC-135As meant that SAC could keep its “special” tankers elsewhere on a more permanent basis.
And while SAC still provided the crews, the Defense Nuclear Agency and the Atomic Energy Commission paid for the new planes’ upkeep. However, the Air Force still refueled the planes to and from their destinations.
Unfortunately, Burning Light was running into other difficulties, through no fault of its own. For one, the missions had to follow a strict schedule so the planes would arrive over Polynesia, almost 3,000 miles away, at the right times.
The French often delayed or completely canceled tests due to bad weather and technical problems. The Air Force couldn’t guarantee that all of the necessary tankers would be ready on such short and irregular notice.
On top of that, the NC-135As relied on water augmentation — or shooting water into the plane’s jet engines during takeoff to produce more thrust. This noisy practice allowed the planes to take off with a full tank of fuel.
But it was too noisy for Hawaii.
Hickam/Honolulu International Airport prohibited water-augmented takeoffs between nine o’clock at night and seven o’clock in the morning — every day. Pressure from Hawaiian politicians and environmental groups prevented the Air Force from getting an exemption from these rules.
“Departures from usual operational procedures and French technical difficulties had turned the Defense Nuclear Agency’s decision to launch the NC-135As largely into ‘guess work,’” the Air Force historians wrote.
In August 1974, the Burning Light missions came to a halt. France continued to test nuclear weapons in the South Pacific for more than 20 years. In all, Paris detonated almost 200 devices in Polynesia.
Today, the Pentagon has special WC-135 Constant Phoenix spy planes to collect nuclear data, whether it be from North Korean nuclear tests or disasters, such as the meltdown of Japan’s Fukushima Daiichi power plant following the 2011 Tohoku earthquake and tsunami.
And while above-ground nuclear tests are largely a thing of the past, the Air Force still scoops up information when friends and allies test out related weapons, especially ballistic missiles.