Kompong Cham Air Base – With fear in his eyes, the RCAF general looked across the plastic table at our group and said we must be either mad, stupid or both. You cannot go into the tunnels, he assured. There are snakes. There are bats. There is no oxygen. They could be full of water. The general’s list of dangers was extensive.
Another officer at the Kompong Chhnang airport stood behind his boss, also bewildered by this strange group of foreigners who wanted to enter the Khmer Rouge tunnel they had long heard stories about, but had never entered.
One soldier used his arms to mimic the movement of a snake, hissing through his teeth for full effect.
Our group had left Phnom Penh early on Saturday morning with the objective of locating and entering the secret tunnel that was dynamited and dug into the hills that roll away from the Khmer Rouge-era military air base in Kompong Chhnang.
The tunnel, it was hoped, would help shed more light on the grand nature and intended use of the Pol Pot regime’s massive air base and associated infrastructure, which is believed to have been built under the supervision of Chinese engineers between 1977 and 1978.
On rare occasions now, a plane might land at the air base, but more often than not, the skeleton crew of military personnel tasked to guard the airport are left to shoo cattle off the still clean and sturdy 2.4 km-long runway.
The quality of the cement runway is unquestioned and stands as a chilling testament to the regime’s planners, their Chinese engineers and slave labor that was used to construct such a grand project in such an out-of-the-way location.
Our group’s leader, Khmer Rouge historian Henri Locard, says he doubts the air base was solely built for Democratic Kampuchea’s air force.
“Since, at the time, [the air force] barely existed at all, one must deduce the air base was for China itself,” Mr Locard said.
“[Not only] to defend the pro-revolutionary and Maoist [Khmer Rouge] regime against the Vietnamese, but also to be used as a base for themselves to be present at the heart of not only Southeast Asia, but Asia itself,” he said.
Many articles have been written about the Kompong Chhnang air base and the estimated tens of thousands of purged eastern-zone Khmer Rouge soldiers who are said to have die or been killed during, and immediately after, the runway’s construction.
“We know from many witnesses and investigators that, for the entire base, the hard labor force was constituted mainly of captured soldiers that were purged at the end of the regime, as they had been accused of having all betrayed the revolution,” Mr Locard said.
“The maximum labor had to be extracted from them before they were put to death.”
But the story of the air base’s tunnel has not been told.
It is rumored though to have been built as a command post and impenetrable bunker for communist forces in the event of an attack on the nearby air base.
Before leaving the airbase for the tunnel, Mr Locard asked the general if there were landmines in the tunnel. No, the general replied, but he couldn’t give any guarantees as he had never been inside.
A wiry 35-year-old air force officer, Chin Saron, was selected to accompany us to the tunnel located about 3 km away from the airbase in the direction of National Road 5 among the surrounding hills. We eventually stopped at the base of a small non-descript hill, sparsely covered in dry scrub.
We gathered our headlamps and torches and Mr Saron led us up a slope along a barely visible path. After about 200 meters we reached a patch of thorny scrub and stopped-the tunnel’s obscured entrance was near.
We pushed through the brush and within 50 meters come across a large hole in the sheer rock wall of the hill. The entrance was 2-meters-high and about 3-meters-wide. Rubble strewn at the entrance appeared to indicate that someone had tried to fill in the access point at some stage.
Some rubbish strewn about and graffiti on the wall outside indicated we were not the first to venture as far as entrance.
What we found on entering the tunnel was astonishing: a six-meter-high cave, finished with reinforced concrete that arched high into the hard rock and carried on straight into the heart of the hill as far as we could see.
Our boots sticking to the muddy ground, we walked forward and within 50 meters the flickering artificial light from our torches was the only thing stopping us from being swallowed by the darkness.
As we ventured further, on the left hand side, was the first chamber in the tunnel, measuring about 10 meters deep and twice as wide. Mr Saron, who stayed at the back of the group, shone his torch on a three-meter long, bright yellow snake among the rocks, which stayed still thankfully stayed put as we walked quietly past.
About 100 meters in, the tunnel looked like it came to an abrupt end. Moving closer, however, we found that the tunnel wrapped around a curved concrete wall, pointing us 90 degrees to the right, down a 1-meter-wide path.
Here, the air thickened, our speech became heavy and bats started to dive toward our group.
The perfectly preserved white concrete walls of the narrow tunnel were reinforced with steel, which is still visible in parts. There was also quite a bit of graffiti. Tags on the walls are written in English and Khmer, and appear to mainly consist of Khmer names. Mr Locard said they could have been written during the UNTAC period in the early 1990s.
Further on we found the next chamber on the left side of the tunnel, followed by another, both measuring about 10-meters-deep by 5-meters-wide. It appeared we had reached the center of the underground complex, directly under the apex of the hill.
The tunnel’s floor consists of dirt, but holes in the concrete walls appear to have been designed for drainage. Wooden planks still extend from the concrete walls along with what looked like copper, perhaps capable of running electricity or a communications system. Above, the concrete continued to arch perfectly, thick and strong.
Mr Locard said the tunnel might have been about 90 percent complete.
“I was amazed to see so much high quality reinforced concrete, perfect domes and curves, with the sockets and holes for draining pipes and electricity wiring,” he said later. “When finished, the whole thing would have been like in a science-fiction film,” he added.
As we went deeper, the tunnel widened again the concrete walls came to an end, returning to the sheer rock encountered at the entrance some several hundred meters away.
Here, the mud came up to our shins, making each step a fight. As this was the end of the dry season, this section of the tunnel floor will be underwater in a few months, after the seasonal downpours begin. The air here was foul and oxygen thin. Bat faeces covered the ground. It is hard to believe that anybody could perform hard labor building an immense tunnel in such an environment.
The final section of wall we encountered, about 400 meters from the entrance, differed from the sheer rock and concrete. Here the walls on either side were sloped and made of loose rock-much like the rubble that had been used to partly fill the tunnel’s opening.
Bats appeared to be escaping through a hole at the peak of the tunnel’s walls, and though there was no obvious space for a person to fit through, it is possible that this could have been a separate entrance to the bunker.
Mr Saron said that locals have long believed there is another entrance to the tunnel, but with the hill here believed to be sown with landmines, no one has gone looking.
Retracing our path back out of the tunnel, we stopped occasionally to again take in the enormity of the carefully-engineered complex. We also noticed that the large yellow snake had not moved from its position.
The lack of documentation about the tunnel and the lack of evidence found inside means we can only speculate about its history.
It is acknowledged that thousands died during the building of the air base, but how many people toiled to their death to construct this surreal subterraneous complex?
The Chinese Embassy in Phnom Penh said last week that it could shed no light on the tunnel complex or the air base that its engineers helped build.
Third Secretary and spokesman Qian Hai said the embassy had no knowledge of either the tunnel or the airport.
“I have no idea of this matter,” Mr Hai said. “I don’t think anyone here has heard of this information,” he said.
Mr Locard, however, is sure of one thing: The Chinese played a big hand in the creation of the air base and the mysterious underground complex several kilometers away.
“I am convinced the Chinese were involved up to the neck into the Khmer experimentation in total revolution and that air base is the most stunning and glaring example of that,” he said.