The United States’ controversial bombing of Cambodia during the Vietnam War killed fewer civilians than American drone attacks under President Barack Obama have done, former US secretary of state Henry Kissinger said on the weekend, a claim labelled as “disingenuous”, foolish and plain wrong by historians and experts.

In a National Public Radio (NPR) interview aired Saturday, Kissinger also said decisions taken by the US during the war, including the massive aerial bombing of Cambodia and Laos, were correct and would be taken by anyone faced with the same circumstances today.

Estimates for the number of civilian casualties of the US bombardment of Cambodia targeting North Vietnamese communists and later the Khmer Rouge – which saw some 2.75 million tonnes of ordnance dropped between 1965 and 1973 – vary greatly, however most scholars agree that they are at least in the tens of thousands.

Unexploded ordnance from the period continues to kill Cambodians today.

In comparison, US drone attacks are estimated to have killed 2,702 to 4,316 people in Yemen, Pakistan and Somalia in total under Bush and Obama, with up to 1,041 civilian deaths, according to the UK-based Bureau for Investigative Journalism.

Little information is known about drone casualties in Afghanistan, where more than 1,000 strikes have occurred.

In the NPR interview, Kissinger, 90, who served as national security adviser to US president Richard Nixon from 1969 until he was appointed secretary of state in 1973, was asked to respond to those critical of his role in the bombing campaign.

“They should study what is going on. I think we would find, if you study the conduct of guerrilla-type wars, that the Obama administration has hit more targets on a broader scale than the Nixon administration ever did,” he said.

When asked about the difference between a drone attack and a carpet bombing, Kissinger responded that despite the stark contrast in accuracy, “the principle is essentially the same”.

“You attack locations where you believe people operate who are killing you. You do it in the most limited way possible. And I bet if one did an honest account, there are fewer civilian casualties in Cambodia than there have been from American drone attacks,” he continued.

Studying the Vietnam War now without prejudice, one would find “that the decisions that were taken would almost certainly have been taken by those of you who are listening, faced with the same set of problems”, Kissinger said. “And you would have done them with anguish, as we did them with anguish.”

While Kissinger’s assertion that drone strikes under Obama had been wider in geographical scale than the bombing of Cambodia may be at least partly accurate, his statement about the civilian casualties is “disingenuous”, said Carlyle Thayer, a Southeast Asia expert at the Australian Defence Force Academy.

While it is impossible to know how many were killed in bombings of communist base areas in eastern Cambodia in 1969-70, if later airstrikes when the Khmer Rouge began to advance on Phnom Penh are included, “at a minimum, several tens of thousands” of civilians perished, he said.

Historian Ben Kiernan writes in The Pol Pot Regime that up to 150,000 civilian deaths resulted from the bombings between 1969 and 1973, though he does not provide a source for these numbers.

Demographer Marek Sliwinski, meanwhile, estimates about 53,000 people, both civilian and military, were killed by bombardments.

According to eminent Cambodia historian David Chandler, while nobody has any reliable evidence of casualties from the US bombings, they “certainly killed a lot more civilians than drones” have.

“The problem is, if you just made a very cold, calculating, military decision, the bombing of 1973 was in fact a sensible thing to do [at the time], because had it not happened, the Khmer Rouge would have taken Phnom Penh [much earlier] and South Vietnam would have had a communist country on its flank,” he said.

The cost of the campaign, however, was enormous, he added, given that they “were bombing the most populated parts of Cambodia”.

There is also, despite Kissinger’s assertion, “no evidence from the time, that this was causing any anguish” to him and Nixon, Chandler said.

After Nixon telephoned Kissinger to demand a covert escalation of bombings in December 1970, he called General Alexander Haig to relay the orders, Kiernan wrote in an article published in 2006.

“He wants a massive bombing campaign in Cambodia. He doesn’t want to hear anything. It’s an order. It’s to be done. Anything that flies, on anything that moves. You got that?” Kissinger reportedly said.

A line between the Cambodia bombings and drone strikes has been drawn before.

A confidential US Justice Department white paper published by NBC News in February last year used the bombing of communist bases in Cambodia as an example to bolster the government’s case for ordering the killings of its own citizens abroad using drones.

Government spokesman Phay Siphan yesterday refrained from criticising Kissinger but said that “we should learn from the past, how the foreign policy of the US came across at the time”.

“Americans talk so much about human rights, so they have to apply the policy,” he said.