Next week, a book by American academic Andrew Mertha will be published, delving for the first time into first-hand accounts of the ties between Democratic Kampuchea and Beijing.

In 2010, the Chinese ambassador to Cambodia, Zhang Jinfeng, claimed that the People’s Republic of China had never politically engaged with what was the Democratic Kampuchea regime. Instead, she argued that assistance was limited to “food, hoes and scythes”.

Others believe the communist country’s influence ran much deeper. Youk Chhang, director at the Documentation Center of Cambodia (DC-Cam), said that the Chinese even trained Khmer Rouge prison guards on how to arrest the enemies of “Angkar”, adding: “The Chinese ‘advisers’ were there from the top all the way down to the lowest level of the Democratic Kampuchea regime.”

The Chinese have always kept quiet about their involvement, historian Milton Osborne wrote in an email this week ahead of the release of a new book that will re-examine the relationship. “For many years the Chinese government was not anxious to have its role in Cambodia during the Pol Pot period given attention and I judge that it would prefer that it not receive publicity now. But its role is now widely known, at least among Southeast Asian specialists, if not among the general public.”

A new book attempts to deconstruct the complex relationship between the two states. In Brothers in Arms: China’s Aid to the Khmer Rouge, 1975 - 1979, which will be published next week in the United States, Andrew Mertha, associate professor of government at Cornell University in New York State, explores China’s role in Democratic Kampuchea, measuring the aid it provided against the influence it had on the regime. The thrust of his argument is that despite China having donated huge amounts to the Khmer Rouge, it had little say in policy due to the low level of competence in both governments.

It’s not the first attempt to tell the story of the Chinese in Pol Pot’s Cambodia: a couple of years ago Huang Shiming, a former Chinese “intelligence worker”, or spy, published a memoir of his experience, which saw him grow up in Phnom Penh, move to China following Mao’s call for revolution during the 1950s, and move back to Cambodia as a spy.

But Mertha’s non-fiction account is different. The academic, who lived in China for seven years and has written two books about Chinese politics, uses personal stories and anecdotes from both Chinese and Cambodian technicians who were in the country at the time, as well as Khmer Rouge officials, to delve into the relationship between the two countries. According to Mertha, both sides spoke of the Chinese providing “the only glimpse of humanity that those Cambodians saw”. He added: “The Chinese would never scold the Cambodians and would get their hands dirty to show them how to get something accomplished, and share their food and cigarettes with them when Democratic Kampuchea cadres weren’t looking.”

According to Mertha, the book tries to consider the countries’ relationship through the lens of individuals and what he refers to as “subnational institutions” rather than national leaders. He added: “The reader is also treated to an extensive and systematic mapping of the bureaucratic landscape of Democratic Kampuchea.”

While much of the world knew very little about Cambodia after the Khmer Rouge took power in April 1975, Pol Pot’s regime maintained diplomatic relations with a number of countries, including North Korea, Yugoslavia, Romania and, until 1977, Vietnam.

But its relationship with China was particularly noteworthy, Mertha said. “Chinese assistance dwarfed that of all the other countries combined. China was treated by the Democratic Kampuchea leaders as a different type of entity than the others,” he said.

This was because of the vast quantity of aid it gave to the Khmer Rouge: firstly, in military form, before and after 1975. It continued throughout the party’s rule in other forms: the building of roads and railways; the establishing of the Kampong Som petroleum refinery and the airfield at Kampong Chhnang; the processing of Chinese crude oil from Daqing oil fields. The relationship also meant that China could exploit Cambodia’s natural rubber production, and work on its electricity grid. There has even been speculation that Phnom Penh’s increased electricity production at the time may have been geared towards eventually repopulating the capital, Mertha said.

During this period, there were several thousand Chinese people in the country, some of whom Mertha interviewed for his book. According to the historian David Chandler, Mertha is the first historian to have done so. Writing in an email this week, Chandler said: “These ‘technical experts’ weren’t hidden, and were often photographed with Democratic Kampuchea officials, although they never speak out in public, and Mertha’s book is the first one to let them talk.”

Mertha said: “They were in Cambodia to try and help their revolutionary brethren and to bring glory to China in its mission to help Cambodia develop under Chinese tutelage.”

According to Mertha however, the idea of Cambodia being China’s “revolutionary brethren” only went so far. While there is a common link made between Maoism and the Khmer Rouge, particularly when comparing Pol Pot’s Four Year Plan in 1976 and China’s Great Leap Forward, the reality of the relationship between the two communist states was quite different, and this was reflected in the relationship between officials in Cambodia. He said: “By 1975, the Chinese, having learned from bitter experience, were warning the Cambodians against rushing too quickly towards realising their revolutionary goals. Khieu Samphan and Ieng Thirith are said to have smiled condescendingly.”

Mertha also contested the widely held view that the Khmer Rouge were Maoist, and claimed, perhaps controversially, that Cambodian communism was far more influenced by its Soviet counterpart.

On top of warnings against jumping into revolution, lack of skills and training in Democratic Kampuchea would frustrate the Chinese who lived in the country, as well as a lack of interpreters, leaving both sides to rely on gestures to communicate.

John Ciorciari, assistant professor in public policy at the University of Michigan and co-author of Hybrid Justice: The Extraordinary Chambers in the Courts of Cambodia, agreed with Mertha that politically speaking, China’s influence in Democratic Kampuchea wasn’t as great as some might think, adding that its “support for disastrous Khmer Rouge policies can easily be overstated”.

He continued: “Mertha has shown that important limits to Chinese influence also existed at the bureaucratic level, as fragmented Chinese aid-administering agencies struggled to work with mismatched, underdeveloped, and sometimes obstinate Democratic Kampuchea institutions.”

Yet despite disagreements on the ground and a lack of influence over Democratic Kampuchea’s policies, China’s aid to the Khmer Rouge regime prevailed. Mertha said: “This is because regardless of who the leader is in China at any given time, even Mao in his waning years, he can only press forward on a finite number (two or three) of key policy preferences.”

The academic believes that China’s relationship with Cambodia – “certainly seen as a feather in Beijing’s cap” – is the first in many subsequent links to what he calls “client states” of the emerging superpower. But he said that the book provides a counter-argument to what has now become a mainstream view: that China’s increasing power is influencing less developed countries. He said: “We need to be more sober in our predictions about China’s engagement abroad, because at the end of the day, China’s influence is only as good as the efficacy of the institutions that manage its relationships with the developing world.”

Ciorciari agreed with this link when analysing aid today, saying: “Capabilities measurable in money or military might do not necessarily translate into policy influence.”

And what of the relationship between China and Cambodia today? Last week, Murray Hiebert, deputy director and senior fellow of the Sumitro Chair for Southeast Asia studies at the Center for Strategic and International Studies (CSIS) in Washington, DC, published an article in the Thai newspaper The Nation claiming that Beijing has been keeping Hun Sen’s government “at arms length” since the increase in opposition protests against the general elections of July last year. He added that although China was until recently Cambodia’s most important patron, there has been a recent shift in its policy towards the Kingdom.

According to Milton Osborne, it’s too early to conclude that there has been a significant change in the countries’ relationship. He said: “We will need a great deal more evidence than is currently available to conclude that this relationship, which has so far served both parties well, is changing in a clear and important fashion.”​