Why the evidence suggests Russia blew up the Kakhovka dam

NEW YORK - Moments after a

major dam in a Ukrainian war zone gave way,

wild torrents cascaded over the jagged remains of the top. But the real problem most likely lay elsewhere, cloaked deep beneath the surface of the raging waters.

Deep inside the dam was an Achilles’ heel. And because the Kakhovka dam was built during Soviet times, Moscow had every page of the engineering drawings and knew where it was.

The dam was built with an enormous concrete block at its base. A small passageway runs through it, reachable from the dam’s machine room. It was in this passageway, the evidence suggests, that an explosive charge detonated and destroyed the dam.

At 2:35am and 2:54am on June 6, seismic sensors in Ukraine and Romania detected the tell-tale signs of large explosions. Witnesses in the area heard large blasts between roughly 2:15am and 3am. And just before the dam gave way, American intelligence satellites captured infrared heat signals that also indicated an explosion.

As the water levels dropped, they fell below the top of the concrete foundation. The section that collapsed was not visible above the water line – strong evidence that the foundation had taken on structural damage, engineers said.

In the chaotic aftermath,

with each side blaming the other for the collapse,

multiple explanations are theoretically possible. But the evidence clearly suggests the dam was crippled by an explosion set off by the side that controls it: Russia.

Battle scars

Even in a war that has razed entire cities, the destruction of the Kakhovka hydroelectric dam in southern Ukraine stands out.

Thousands of people were displaced by flooding from one of the world’s largest reservoirs, which was

vital for irrigating farmland

considered the bread basket of Europe. The disaster puts global food supplies for millions at risk and could threaten fragile ecosystems for decades.

The dam was visibly scarred by fighting in the months before the breach. Ukrainian strikes had damaged one part of the roadway over the dam, and retreating Russian troops later blew up another. Last month, satellite images showed water flowing uncontrolled over some of the gates.

This has led to suggestions that the dam may have merely fallen victim to the accumulated damage, which Russia has seized on to deny responsibility.

But multiple lines of evidence reviewed by The New York Times, from original engineering plans to interviews with engineers who study dam failures, support a different explanation: that the collapse of the dam was no accident. The catastrophic failure of its underlying concrete foundation was very unlikely to occur on its own.

Given the satellite and seismic detections of explosions in the area, by far the most likely cause of the collapse was an explosive charge placed in the maintenance passageway, or gallery, that runs through the concrete heart of the structure, according to two American engineers, an expert in explosives and a Ukrainian engineer with extensive experience with the dam’s operations.

“If your objective is to destroy the dam itself, a large explosion would be required,” said Michael W. West, a geotechnical engineer and expert in dam safety and failure analysis, who is a retired principal at the engineering firm Wiss, Janney, Elstner. “The gallery is an ideal place to put that explosive charge.”

Engineers cautioned that only a full examination of the dam after the water drains from the reservoir can determine the precise sequence of events leading to the destruction. Erosion from water cascading through the gates could have led to a failure if the dam were poorly designed or the concrete was substandard, but engineers called that unlikely.

Ihor Strelets, an engineer who served as the deputy head of water resources for the Dnipro River from 2005 until 2018, said that as a Cold War construction project, the dam’s foundation was designed to withstand almost any kind of external attack. Mr Strelets said he, too, had concluded that an explosion within the gallery destroyed part of the concrete structure and that other sections then were torn away by the force of the water.

“I do not want my theory to be correct,” he said. A large explosion in the gallery might mean the total loss of the dam. “But that is the only explanation,” he said.

Waking to Water

In the predawn hours of June 6, residents living close to the dam in both Russian-controlled and Ukrainian-controlled territory heard explosions and strange rumblings, they said later.

They were no strangers to the sounds of fighting. For months, the two armies had traded artillery volleys across the Dnipro River. But this time seemed different – and soon it was clear why.

For those closest to the dam, built in the 1950s by the Soviet state, the rush of water was almost immediate. It took longer for the floods to make their way farther downriver, but when they did, they came fast and then did not begin to subside for more than a week.

A prime target

The relatively spindly sluice gates and cranes and the ribbon of roadway above the water line seemed to offer an easy target for an attack aimed at destroying the Kakhovka dam.

But most of the dam’s enormous mass was hidden below the surface of the water, according to diagrams of the structure obtained by the Times and detailed descriptions by Mr Strelets, who said he has spent months at the Kakhovka dam and around the reservoir.

That mass consisted of a rounded tower of nearly solid concrete some 20 metres high and as much as 40m thick at the bottom, Mr Strelets said. Built in sections, that colossal barrier ran between earthen embankments on either side of the channel and did much of the work of holding back the waters of the reservoir.

The sluice gates sat atop that barrier, opening and closing to adjust the water level. Visual evidence assembled by the Times shows clear damage to the roadway and to a few of the sluice gates on one side of the channel in the months before the breach of the dam.

Despite that damage and a white-water cascade tumbling from the vicinity of those gates, engineers said the foundering of an entire section of the dam was more likely to be related to the blasts picked up by seismic sensors and to an infrared signal that US officials said was picked up by a satellite, indicating the heat of an explosion.

The seismic signals were picked up on two sensors, one in Romania and one in Ukraine, said Ben Dando, a seismologist at Norsar, a Norwegian organisation that specialises in seismology and seismic monitoring. The signals were both consistent with an explosion, he said – and not, say, the collapse of the dam on its own.

He said that the network could determine the time of an explosion to within a couple of seconds but that the location of the blasts was less certain. For example, Norsar could locate the 2:54am signal to have originated within a zone 20 or 30km across that included the dam.

A specific time stamp for the infrared signal was not available, but a senior US military official said that it was picked up shortly before the dam collapsed.

A senior American military official said that the United States had ruled out an external attack on the dam, like a missile, bomb or some other projectile and now assesses that the explosion came from one or more charges set inside it, most likely by Russian operatives.

Gregory B. Baecher, an engineering professor at the University of Maryland and a member of the National Academy of Engineers, also said the scale of the breach indicated that the underlying concrete barrier had failed, suggesting that charges had been set deep in the structure.

“If they put explosives in the gallery, that would explain a lot,” he said. A large explosion there, he said, “would just rip up all the concrete structure”.

Nick Glumac, an engineering professor and explosives expert at the University of Illinois at Urbana-Champaign, said the size of the necessary charge could vary widely depending on the exact way in which the explosives were set and the precise objective.

“It’s worth remembering that you don’t have to pulverise the dam section – just break it enough, such that the water pressure is enough to tear it away,” he said.

Still, he said that based on diagrams of the dam and the latest imagery of the destroyed foundation, “it’s hard for me to see how anything other than an internal explosion in the passageway could account for the damage”. He added: “That’s a massive amount of concrete to move.”

Using the gallery might have another advantage for anyone seeking to hide their tracks. According to Mr Strelets, the gallery had only two entrances, including one inside the machine room located in a building to one side of the dam.

Mr West, who is also a former Army combat engineer officer, noted that would allow the dam to be rigged out of sight of spy satellites, drones or witnesses on the ground. Early-morning drone footage showed that the initial breach in the dam occurred not far from the machine room. NYTIMES