Sydney Schanberg, who reported for the New York Times in Cambodia, recalled the US Embassy’s air attaché, Col David Opfer’s briefing, which he described as severe. Then US foreign secretary Henry Kissinger had downplayed the number of casualties.

“He said the casualties weren’t severe,” Schanberg, who died in 2016, told The Intercept. “He said there were 50 dead and some injured.” Opfer admitted that he didn’t actually know the number. “Even then I wasn’t sure how many,” he explained.

Schanberg, who later won a Pulitzer Prize for his reporting from Cambodia, was sceptical of the pronouncement and set out to see for himself. He was thrown off a Cambodian military flight to Neak Luong, but Schanberg’s fixer Dith Pran got them to the town by boat, and they interviewed survivors until local officials detained the journalists for taking photographs of “military secrets.”

The US Embassy, meanwhile, tried to wrest control of the story by arranging for a group of five Western reporters to take a quick look around with little opportunity to speak to townspeople.

Schanberg and Pran, who spent a day and night under house arrest, watched their press colleagues through the window of the building where they were confined. “They didn’t see enough to write a detailed story and they hadn’t talked to anybody,” said Schanberg, noting that the pool of reporters were only on the ground for about 20 minutes.

Ny Sarim told The Intercept that soldiers from the US-allied Cambodian military also kept residents from making their way downtown, but that even from a distance, the damage was unmistakable. When she finally got through the cordon, she saw massive craters and twisted metal. “It was a total wreck,” Schanberg told me. “Everything had been hit.”

Schanberg’s August 9, 1973, front-page Times story on Neak Luong emphasized Opfer’s minimization of the damage; a second article and an editorial soon after detailed U.S. efforts to thwart Schanberg from covering the story.

In a confidential cable back to Washington, US Ambassador Emory Swank mentioned “the New York Times correspondent’s accusation that the air attaché office attempted to block journalists’ access to Neak Luong” and defended the officer.

“Colonel Opfer has done well in trying circumstances,” he stated, while casting the foreign press corps as “demanding and hostile.” Opfer told The Intercept that the Cambodian military had detained Schanberg and Pran. “They always get things mixed up and don’t tell it as it really is,” he said of the press.

Schanberg took a different view. Opfer, he said, “was absolutely unskilled with the press. I felt bad for the man, in a way, because he was telling us what he had been told to tell us. A lot of the senior officers felt that we didn’t give anybody a fair break – but the Cambodians weren’t getting much of a break, were they?”

Officially, 137 Cambodians were killed in the Neak Luong bombing and 268 were wounded, according to the US Embassy in Phnom Penh. Months later, Enders, in a confidential December 1973 cable that went to Kissinger and then-Secretary of Defence James R. Schlesinger, confided that the US had actually paid out solatium for 273 dead, 385 seriously wounded, 48 who suffered “mutilation,” and 46 victims of slight injuries. All told, that figure – 752 people hurt or killed – was 86 percent higher than the official number.

Enders stated that the US had not sought to verify the numbers, but that the tally had been certified by the Cambodian regime. The final number of wounded and dead, he noted, “is higher than the official count given by [the Cambodian government] to the press and therefore should not be released.”

In the December 1973 cable, Enders admitted that the U.S. had never established a policy for “the payment of medical expenses for persons injured by US errors,” and that the bombing of Neak Luong was “the only such incident which has occurred in Cambodia.”

But just a day after the Neak Luong bombing, a State Department cable referenced a “second accidental bombing” at Chum Roeung village that killed four to eight people and injured up to 33. The Pentagon blamed the “error” on a F-111 bomber’s “faulty bomb-release racks.” By then, the US had dropped hundreds of thousands of tons of bombs throughout the countryside and killed, according to experts, as many as 150,000 Cambodians.

Two weeks after the bombing of Neak Luong, Swank, the US ambassador, publicly signed an agreement on compensation with the Cambodian government.

“We desire to compensate, insofar as possible, the survivors of the tragedy,” he said in a brief speech, adding that the US would pay $26,000 to rebuild the damaged hospital in Neak Luong and provide $71,000 in equipment.

The next of kin of those killed, according to press reports following his speech, would receive about $400 each. Considering that in many cases, the primary breadwinner had been lost for life, the sum was low: the equivalent of about four years of earnings for a rural Cambodian at the time.

The financial penalty meted out to the B-52 navigator whose failure to flip the offset switch killed and wounded hundreds in Neak Luong was low too. He was fined $700 for the error. By comparison, a one-plane sortie, like that which bombed Neak Luong, cost about $48,000 at the time. A B-52 bomber cost about $8 million.

In another confidential cable sent in December 1973, Thomas Enders made a final accounting of solatium payments to those who had lost a relative in Neak Luong. They had actually not received the $400 per dead civilian that they had been promised. In the end, the US valued the dead of Neak Luong at just $218 apiece.

• The Intercept report