Horizon Special: What Sank the Kursk?
BBC TWO 9.00pm Wednesday 8th August 2001

NARRATOR (BERNARD HILL): One year ago the Russian submarine the Kursk sank in a terrible disaster. 118 men died. It was a tragedy that shocked the world.

OLGA KOLESNIKOV: It was a catastrophe. Far more than just 118 men died in this disaster. The hopes of their wives and children died with them.

NARRATOR: The Kursk now lies at the bottom of the sea, the bodies of her crew still entombed inside her. To many this tragedy remains incomprehensible, for the Kursk had been built to be unsinkable.

ADMIRAL VALERY ALEKSIN (Russian Navy, retired): When I first heard about this it was a mystery to me 'cos it was supposed to be practically impossible to destroy this submarine.

COMMANDER VIKTOR ROZHKOV (Captain of the Kursk 1991-1997): I couldn't get my head round the idea that the Kursk could sink. It couldn't, that just couldn't happen.

NARRATOR: For a whole year the mystery of what sank the Kursk has been veiled in confusion and secrecy. For months the Russians controversially claimed that their submarine must have been sunk by a foreign power, but a string of new scientific discoveries have emerged which suggest that the Russians were wrong and they offer a very different reason why this unsinkable vessel was destroyed.

CAPTION: Severomensk Naval Base, Barents Sea, 9th August 2000

NARRATOR: Last summer the Russian northern fleet departed for the Barents Sea to engage in a series of war games. Around 30 warships prepared to set sail. These exercises would give them a chance to test their most modern weaponry and equipment.

ADMIRAL VALENTIN BETS (Russian Navy, retired): All the crews and sailors were very excited about these naval exercises. After all, they don't happen very often.

NARRATOR: At the heart of these exercises was an extraordinary submarine, the vessel said to be almost indestructible, the Kursk. The Kursk was an attack submarine, the pride of the fleet, one of Russia's most secret weapons. She bristled with missiles and torpedoes and she could survive for months underwater without being detected.

VIKTOR ROZHKOV: Wherever the Kursk went we were feared. We were feared. The Kursk was feared.

NORMAN POLMAR (U.S. Naval analyst): This submarine is one of the most potent anti-ship weapons ever developed. I would say that among the weapons in the world today that threaten a large warship the Kursk is very close to the top of the list.

NARRATOR: The Kursk was not just powerful. She was also built to be invulnerable. She was as tall as a six-storey building and 150 metres long, more than the length of two Jumbo jets. Her size alone made her hard to destroy, but to make her unsinkable she had been given a double hull. She had an outer hull made of solid steel, but inside this was another steel hull over 5 centimetres thick containing the crew. Western submarines do not have this double protection. Within this cocoon she was also divided into nine separate watertight compartments. The Kursk was built to take a direct hit and yet still survive.

VIKTOR ROZHKOV: You can't take the Kursk out even with a torpedo. Yes, there may be some damage, but she'll always be always to come to the surface.

NARRATOR: On August 10th 2000 the Kursk joined the rest of the fleet in the Barents Sea and the exercises began. The northern fleet spent the first day test firing its weapons and the Kursk successfully launched the Russian Navy's most advanced cruise missile from underwater. Everything was going well. The next day disaster struck.

CAPTION: 12th August 2000

NARRATOR: On that crucial day at around nine in the morning the Kursk made what would be its last radio contact when it received the go-ahead to carry out a mock attack on the northern fleet.

VALERY ALEKSIN: The Commander would have given the order to rise to periscope depth to carry out reconnaissance of the area to locate and identify the rest of the fleet.

NARRATOR: The northern fleet waited for the Kursk to begin her mock attack. They waited all day, but they were never to hear from the Kursk again. She had already sunk to the bottom of the sea. When news of the disappearance of the Kursk became public there was every hope her crew were still alive, trapped inside her. Many believed that if the Russian Navy could only reach the sailors before they ran out of air they would be saved. For nine days, while the relatives held vigil, the Navy repeatedly tried to reach them and the world waited.

VIKTOR ROZHKOV: I couldn't sleep or eat. It was difficult for me to do my job. I was waiting for each new television report, every radio report to find out what was happening.

NARRATOR: Meanwhile, 100 metres underwater at the bottom of the Barents Sea divers had found the Kursk and were trying to open the submarine's hatches. There were rumours they heard tapping from the crew trapped inside, but as each day passed hope faded. No one knew how long the oxygen supplies inside the Kursk could last or whether anyone could survive the near freezing temperatures. Eventually a team of Norwegian divers managed to open the submarine. They found the entire vessel flooded. All 118 men on board were dead. At this stage no one had any idea what had caused the disaster. As the tragedy reverberated around the world the Russians began the grim task of trying to raise the bodies of the dead. In the end they managed to bring only twelve men to the surface. One of them was Lieutenant Dimitri Kolesnikov. Dimitri's story was to become the most potent symbol of the tragedy of the Kursk. His body was discovered at the rear of the submarine in the ninth compartment and with him they found a letter he had written in the hours following the disaster. It was carefully wrapped in plastic to keep it dry and it gave the world the only insight into what it had been like to die on the Kursk. Dimitri had written the letter to his new bride. Just four months earlier Dimitri had married Olga and a few weeks before the Kursk's final voyage Olga had visited her husband on the submarine.

OLGA KOLESNIKOV: It was Dimitri's sixth year on the Kursk and he was really proud of that. He said I shouldn't worry. There was no reason for me to worry because it's such a modern submarine, it's so reliable, so new and while he was on board the Kursk nothing bad could happen to him.

DIMITRI KOLESNIKOV: This is how I usually spend my time in an emergency.

OLGA KOLESNIKOV: In an emergency?

DIMITRI: I lie here like this and have a little sleep and then the alarm goes and bang, I keep hitting my head on that bit, but it's never boring. There's always something going on.

OLGA: Go on Dimitri, please take me to sea with you.

DIMITRI: I can't. Having women on board a boat is bad luck.

OLGA: But I'll sing and dance and smile at everyone.

DIMITRI: If you're going to smile at everyone then it's totally out of the question for you to come along.

NARRATOR: The letter they found on Dimitri's body showed that for some of the crew death was not instant. 23 of them survived for several hours in an air pocket at the rear of the submarine.

OLGA KOLESNIKOV: Olga, I love you. Please don't be too upset. It's 13.15. All the crew from the sixth and seventh compartments have moved to the ninth. There are 23 of us here. We took this decision because of what has happened.

NARRATOR: Dimitri's letter conjured up a horrifying scene. Survivors shivering in near freezing temperatures hoping for rescue as all the while they used up their precious oxygen. They cannot have lasted long. Dimitri's final entry was just four hours after the Kursk sank.

OLGA KOLESNIKOV: None of us can escape to the surface. It's too dark to write in here. I'll try and write by touch alone. It seems as though we've got little chance, no more than 10 or 20%. I hope at least that someone will read this. Don't despair. Kolesnikov, 15.45.

NARRATOR: The death of all 118 submariners was a national tragedy. It became all the more urgent for the Russian authorities to solve the mystery of what had sunk the unsinkable Kursk. Meanwhile, divers studying the vessel had discovered something shocking.

NORMAN POLMAR: The front of the bow section had been ripped open. The entire hull was distorted. The forces that inflicted this damage were tremendous.

NARRATOR: The entire front section of the supposedly indestructible submarine had been completely devastated. It soon became clear that this destruction must have happened when something, or someone, had set off the entire arsenal of torpedo warheads on board the submarine. To create this level of devastation the warheads must have suddenly gone off, all at once. It was inexplicable. Warheads do not explode spontaneously. The question of what, or who, had set off the warheads was to become the central mystery of the sinking of the Kursk. The Russians immediately began to consider everything that could possibly have set off the warheads, however far-fetched. Sabotage, terrorism and even a UFO were all briefly considered. The suggestion a World War Two mine had sunk the Kursk was dismissed as very unlikely. It would hardly have damaged her. Another theory that a missile fired from a Russian warship had accidentally hit the submarine was also ruled out. These missiles cannot hit targets underwater, but within Russia one other explanation for the tragedy began to gain credibility that seemed to explain both what could have caused
the warheads to explode and crucially who was responsible.

VALENTIN BETS: I remember exactly where I was when I first heard the news of the Kursk disaster. I was gardening in the country and as soon as I heard it immediately I had only one thought. This could only have been caused by a collision with a foreign submarine.

NARRATOR: It is now accepted that two American submarines were indeed spying on the Russians in the Barents Sea at the time of the disaster. Even though the Cold War is long over, both sides still monitor each other's weaponry and tactics in case of future hostilities.

NORMAN POLMAR: We know that there were two US submarines in the Barents Sea. They were certainly in the area monitoring radar transmissions, communications, underwater transmissions, underwater noises.

NARRATOR: One of the tasks of the American submarines was to track the movements of the Kursk and the Russians believed that this would turn out to be the key to the tragedy. The Russians believed that it all began when one of the American submarines monitoring the Kursk lost its way. Submarines cannot see each other underwater. They have to use sonar to listen for the sound of each other's engines and propellers, but sound can be hard to pick up underwater. The Russians believed that the American spy submarine had lost track of the Kursk and in the confusion had ended up heading straight towards her.

VALERY ALEKSIN: This immediately started a huge fire in the first compartment.

NARRATOR: The Russians believed that this fire rapidly became so hot that it set off the warheads housed in the front of the Kursk.

VALENTIN BETS: Then the torpedoes on the shelves started to catch fire which caused a large explosion.

VALERY ALEKSIN: This obliterated the front compartment and destroyed the submarine and most of her crew.

NARRATOR: This Russian scenario is credible. One of the best kept secrets of the submariner's world is that collisions between submarines have happened many times before.

VALERY ALEKSIN: A total of 25 collisions have been recorded since 1967 and many of these, eleven of them, occurred near the naval bases in the Barents Sea, which is where the Kursk disaster happened.

NARRATOR: As soon as the Russians made their allegation of a collision the Americans denied it. They said no American submarine could have survived such a collision without suffering enormous damage and yet no damaged American submarine had surfaced anywhere in the world, but then the Russians produced evidence that seemed to show an American submarine had indeed been damaged and sought refuge in the nearest friendly port for repairs. The Russians published a photograph taken by a military satellite of a naval base in Norway dated just six days after the Kursk sank. It showed two warships docked in port, but it also showed another vessel that was longer and slimmer than the warship. Russian analysts said it had the outline of a nuclear powered submarine exactly the same type as those known to have been spying on the Kursk. Nuclear submarines usually operate in extreme secrecy and spend months underwater. For one to be seen in port is very unusual and this type of submarine the Russians said could only have come from one country.

VALENTIN BETS: The Norwegians do not have nuclear submarines themselves so this must be an American submarine. Why would it be in a Norwegian port? It might have come to replenish its supplies, but we can rule that out because nuclear submarines are totally self-sufficient. While at sea they don't have to pull into port for resupplying, so why, in this case then, did it come to this port? It must have been to repair the damage sustained in the collision.

NARRATOR: At first the satellite photograph appeared to be strong evidence for a collision, but the Americans disagreed.

NORMAN POLMAR: These photos are certainly not conclusive evidence that a US submarine was in any way involved in the Kursk disaster. These photos are not even clear enough to determine if it is a US submarine. They do not reveal any damage, any direct involvement. Let's assume it is an American submarine, it is one of the submarines that was in the Barents, which are two major assumptions. It could be there to unload Norwegian intelligence officers who were on board for the operation, or could it be to unload tapes, data, that they want flown back to Washington because in view of the Kursk's loss we're now anxious to review this data. But this photograph indicating evidence of a collision? Absolutely not, absolutely not.

CAPTION: October 2000

NARRATOR: The Russians were determined to prove the collision theory and three months later they believed they'd found definitive evidence. The Russian Navy's most senior Admirals hastily gathered to look at some new video footage. It had been taken by divers and was of an area on the right-hand side of the Kursk just behind the devastated bow. It showed, they claimed, evidence of a collision.

RUSSIAN ADMIRAL: You can see there was an impact there, a sliding blow, a scrape. That's the place. We specially took a lot of footage of this, but that's not a crack, that's where the hull was slit open.

VALERY ALEKSIN: It's evidence of a very large metal object coming from the other direction and inevitably this cannot be anything except evidence of a collision with a foreign submarine.

NARRATOR: The Russians believed that following the collision the American spy submarine had sliced open the side of the Kursk with its keel leaving behind the telltale damage. Once again the Americans denied it. The dents and scrapes they said had been caused simply by the explosion of the warheads.

NORMAN POLMAR: Major damage of this kind is exactly what you would expect for a submarine that's had a horrific explosion that just ripped the bows apart, disfigured the entire submarine, but to imply that this down here, this particular bit of damage, is in any way evidence, evidence that the submarine was in a collision is just ridiculous. Absolutely ridiculous.

NARRATOR: For months claim and counter-claim continued, but by now Russian suspicions were widely accepted. Russian government authorities were claiming the Kursk had been sunk in a collision with an American submarine. Yet far away from Russia a group of scientists had discovered some crucial information. It was to cast doubt on the entire collision theory.

CAPTION: Blacknest, Berkshire, UK

NARRATOR: Hidden in the English countryside is an unusual institution, the British government's seismic monitoring station, Blacknest. Here scientists have equipment which can detect underground nuclear tests from anywhere in the world. Their seismometers will register any large explosion, but they had picked up the seismic signal of the explosion which sank the Kursk.

DR PETER MARSHALL (Blacknest Seismic Research Centre): When we first started to analyse the seismic data from the Barents Sea the first thing we noticed was this very large seismic event here. It's very large amplitude, in fact it's equivalent to an earthquake with a magnitude of about 4 on the Richter scale.

NARRATOR: 4 on the Richter scale is equivalent to a substantial earthquake. This large seismic event was the explosion of the mass of torpedo warheads in the front compartment, but then the scientists noticed something else, another event which had been captured by their seismometers.

PETER MARSHALL: What was really quite extraordinary was that 2 minutes 15 seconds before the large event arrived there was indeed another much smaller event from the same area, an event which is actually about one hundredth the size of the main event.

NARRATOR: 2¼ minutes before the large explosion something much smaller had happened to the Kursk, something so small it barely registered on the seismometers. This was the key to the mystery, the fingerprint of what had caused the torpedo warheads to explode. Discover what it was and you would know what had sunk the Kursk. Some Russians, of course, believed it was the signal of a collision.

VALERY ALEKSIN: The first signal that was picked up by seismic stations must be the result of a collision between two submarines.

NARRATOR: But when the scientists at Blacknest began to analyse the small signal to try to find out what it was they discovered something quite different. Every seismic event has its own unique signature. An earthquake produces one kind of signal, a volcano produces another and an event like a collision yet another.

PETER MARSHALL: We're able to analyse the nature of the seismic disturbance, whether it's from an earthquake, a volcano, an underground explosion, whether it's nuclear or whether it's a quarry blast or even a seismic disturbance created by a vehicle moving down the road close to the seismometer. We can take this data and analyse it in an attempt to identify the nature, the origin of that seismic signal.

NARRATOR: Marshall's team decided to enlarge the mysterious first small signal and compare it with the large signal to look for differences. If the first signal was the fingerprint of a collision it should look completely different to the large signal which was from the explosion of the warheads. What they discovered stunned them.

DR DAVID BOWERS (Blacknest Seismic Research Centre): Now two seismic signals are almost never the same shape. This almost never happens, so I was expecting to see big differences. Now, when I compared them I was astonished to see this. The two signals almost perfectly matched. They're very similar. In other words, the first signal had also been caused by an underwater explosion.

NARRATOR: It seems the Russians were wrong. The small signal had been caused not by a collision but an explosion. There was no evidence of a collision. The hunt to discover what sank the Kursk would have to start from scratch. Scientists considered everything capable of causing a blast smaller enough to create a signal of exactly this size, but whatever they thought of would have caused too big an explosion. They ruled out the nuclear reactors which powered the Kursk's engines. They ruled out the cruise missiles she had been carrying. Even the explosion of a single torpedo warhead was too large.

NORMAN POLMAR: That raises the question of what else was there in the forward section of the submarine that could have exploded?

NARRATOR: Some scientists now believe they've found the answer. They focussed on something that was dismissed by the Russians and ignored by the Americans, yet it is capable of causing an explosion of exactly the right size. It is something that cannot itself explode, something that cannot even catch fire, that seems utterly unconnected with the disaster, but it was in the front compartment and may well have caused the whole tragedy. The culprit may well be a colourless, odourless liquid with almost the same chemical make-up as water, a liquid called HTP, or hydrogen peroxide. When this chemical breaks down it releases oxygen and so is sometimes used to supply oxygen to torpedo engines. A torpedo is driven through the water by a propeller powered by a small engine. These engines burn fuel which is stored in a tank, but to do this they need oxygen and because there is no available oxygen underwater they all have to carry their own supply. The oxygen supply normally used by the Russians, unlike almost all other countries, is a small tank of HTP. To the Russians the idea of something as apparently innocuous as HTP causing the Kursk disaster seemed nonsensical. HTP cannot explode spontaneously. It isn't even flammable.

DR BARRIE MELLOR (Propellant chemist): For example, if we take a sample of liquid HTP and we play a high temperature flame across it nothing happens. It simply is not possible to set light to liquid HTP.

NARRATOR: All that happens to hot HTP is that it evaporates. The Russians had long believed it was impossible for a chemical as apparently harmless as this to have caused any kind of disaster.

VALERY ALEKSIN: These torpedoes had been used for 25 years. They've been fired in training thousands of times and in all that time there'd been no emergencies and no explosions.

NARRATOR: But some scientists now think the Russian confidence in their HTP power torpedoes was misplaced and they believe this because of a little known event that happened long ago. On June 16th 1955 the British submarine HMS Sidon was moored up in Portland harbour on the south coast of Britain. She had taken on board an experimental torpedo. it was code-named the Fancy and was powered by HTP. After the torpedo had been loaded, but before the submarine left harbour, disaster struck. Inside the Sidon the casing of the Fancy torpedo exploded.

MAURICE STRADLING (Torpedo designer): The effects were absolutely devastating. The front half of the torpedo shot out through the closed front door of the torpedo tube allowing the sea to flow in.

NARRATOR: Although the torpedo warhead itself never exploded, the submarine sank. Most of the crew were rescued, but 13 men died. An inquiry into the disaster was called to try to discover what had gone wrong. When they examined the wreck of the submarine the investigators noticed one key thing about the Fancy. Inside the torpedo a stainless steel pipe containing HTP had burst and the enquiry concluded that this was what had caused the accident, that somehow the normally safe HTP must have been responsible for the explosion, but they could not work out precisely how. The report was published without solving the mystery.

MAURICE STRADLING: On the face of it it's very difficult to imagine HTP being responsible for the side-on explosion. It's very difficult to see why it should be any more dangerous than a bottle of compressed air.

NARRATOR: Despite not solving the mystery, the Royal Navy never used HTP in its torpedoes again. 45 years later the Kursk disaster prompted torpedo designer Maurice Stradling to find out exactly how HTP could cause an explosion. He began by looking again at the Fancy.

MAURICE STRADLING: This is a Fancy torpedo and it's identical in every respect with the torpedo that failed on HMS Sidon 45 years ago, except that this torpedo has had sections of its hull removed so that you can see what's inside. What you can see immediately is that this torpedo is simply a closed metal tube with metal components inside it.

NARRATOR: The sealed tube containing metal components doesn't sound dangerous, yet there is something about HTP in these conditions which can lead to an explosion. Because when HTP comes into contact with certain metals it may not explode, it may not catch fire, but it does react.

BARRIE MELLOR: Hydrogen peroxide is a very simple chemical. it's composed of hydrogen and oxygen, just as is water, so you might think it was quite harmless. In reality when hydrogen peroxide comes into contact with some metals it breaks down producing oxygen and water and this reaction can be really quite violent.

NARRATOR: When certain metals, like copper and brass, come into contact with HTP they sever the atomic links holding the chemical together. This breaks the liquid down into oxygen and steam which is not in itself dangerous, but in doing this something extraordinary happens. When it becomes hot gas HTP expands in volume an astonishing 5,000 times and this is what may have caused the tragedy of the Sidon. Stradling concluded that inside the Fancy when the stainless steel pipe containing HTP had burst it sprayed the liquid around the inside of the torpedo casing and then the one dangerous thing that could happen happened. The HTP splashed over reactive metals - in the case of the Fancy components made from copper and brass.

MAURICE STRADLING: The HTP reacted on bare metal inside the torpedo and gas was created that pressurised the hole internally creating a virtual time bomb.

NARRATOR: What happened next to the Fancy can clearly be demonstrated in the laboratory with a test-tube.

BARRIE MELLOR: This is an experiment in which we're going to try to replicate what happened to the torpedo on board HMS Sidon. The glass tube represents the sealed hull of the torpedo. Inside we have some metal fragments and that represents all of the metal components and fittings inside the torpedo. Now if you can imagine that the holding tank containing the HTP springs a leak. The HTP would then be showered within the case of the torpedo and react with the metal surface very violently.

NARRATOR: As the HTP turned into gas it rapidly expanded and inside the torpedo casing the pressure from this volume of gas became overwhelming. The results were lethal. Just the torpedo casing exploded, not the warhead itself, yet this small explosion was enough to kill 13 men and sink the Sidon, but what had made the HTP leak out of its pipe in the first place? This was a puzzle that 45 years ago the enquiry did solve. They believed that the HTP pipe burst because someone had accidentally started the torpedo engine while it was still inside the submarine. Torpedo engines are not meant to start out of water. The enquiry believed the engine over-pressurised the fuel system rupturing a pipe containing HTP. Using this knowledge from the Sidon tragedy, it is now possible to explain how, 45 years later, HTP could have destroyed the Kursk.

CAPTION: 12th August 2000

NARRATOR: On the morning of the tragedy we know the Kursk was preparing to test fire a torpedo. This torpedo would have been in the Kursk's front compartment. Maurice Stradling believes the disaster began when someone made the simple error of starting the torpedo engine too soon, while it was still inside the submarine.

MAURICE STRADLING: If the torpedo was accidentally started then because the propellers were not in the water there would be nothing to control the speed of the engine. The engine would have over-revved and the HTP pipe would have burst allowing HTP to spray into the inside of the torpedo hull and the whole ghastly chain of events would be in place.

NARRATOR: According to this theory the HTP would have immediately reacted with metals inside the torpedo casing.

BARRIE MELLOW: An unstoppable reaction occurred producing oxygen gas and water vapour. The gases would have built up to a very, very high pressure and eventually when the casing of the torpedo did fail, it failed in a very catastrophic manner.

NARRATOR: This small explosion, not of the torpedo warhead but of the torpedo's casing, would have created the first tiny seismic signal detected by scientists hundreds of kilometres away, but back on the Kursk the volatile mixture of torpedo fuel and oxygen would have burst out of the torpedo casing in a fireball.

NORMAN POLMAR: In two minutes people are fighting a fire trying to determine what's going to happen, what they can do to put it out.

NARRATOR: For 2¼ minutes the scientists' instruments recorded nothing. This would have been the last chance to save the Kursk. During this time if only the sailors could have controlled the fire the submarine would have been saved. Instead it must have raged on engulfing the real threat to the Kursk, the stacks of stored torpedoes in the front compartment.

MAURICE STRADLING: The fire would have been centred on the warheads, on the other torpedoes in the storage racks, so it wouldn't take long for those warheads to detonate as a result of the heat that surrounded them.

NARRATOR: After 2¼ minutes the heat would have grown so intense it was enough to detonate the racks of torpedo warheads in one massive and fatal explosion. This was the second huge seismic signal that was detected.

NORMAN POLMAR: The detonation is so catastrophic it tears open the submarine admitting tons of water. This destroys all life in the forward portion of the submarine within a matter of a second or two.

NARRATOR: Further back in the Kursk Dimitri Kolesnikov would have known the front of the submarine had suffered a colossal explosion. He and 23 other survivors gathered together in the rear compartment.

VIKTOR ROZHKOV: There was no source of electricity, there was no power. There may have been some small emergency lights which were on, which are not very bright, but that's it.

NARRATOR: In the back of the Kursk Dimitri wrote his last words to his wife.

OLGA KOLESNIKOV: It's too terrifying to even think about because death should be instantaneous. That's the only acceptable way to die and yet I know that Dimitri managed to stay alive for quite a while.

NORMAN POLMAR: And then over the next few hours, possibly a day, the cold, the hypothermia, the build up of pressure, their own carbon dioxide is slowly killing them. A horrible way to die.

NARRATOR: Only if the remains of the Kursk's front compartment is raised from the sea floor and the wreckage examined for evidence will we know for sure if it was the HTP inside a torpedo which caused the disaster, but at the moment it seems doubtful this will ever happen, for although the Russians are trying to raise the submarine, they plan to leave the front of the Kursk on the seabed.

NORMAN POLMAR: The irony is that the bow section of the submarine, the torpedo room, where there may be some evidence left despite the devastation as to what caused the disaster, under the salvage plan is going to be left on the ocean floor. It's, it's the one area that could give us the answer to what happened and that part is not planned for salvage.

NARRATOR: The Russians have recently begun to abandon their claim that it was a collision with an American submarine which sank the Kursk. They have now started to suggest that a torpedo explosion might indeed have somehow caused the tragedy, but unless it is finally proven whether it was the HTP that was responsible, then the Russian torpedoes will never be given the safety modifications to ensure tragedies like the Kursk do not happen again.

OLGA KOLESNIKOV: The truth about this must be told for the sake of all those Russian sailors who have yet to go to sea because only when we face up to what really went on will we be able to stop disasters like this one from ever happening again.

Update 7 May 2002
Since this programme was first shown, Russian officials have admitted that "unfounded trust" was placed in torpedoes powered by HTP. They have now taken this type of torpedo out of service.