A year after a fatal accident aboard the nuclear-powered submarine Losharik, it remains out of service. The accident cost 14 elite ‘hydronauts’ their lives and damaged the titanium-hulled submarine. While the international submarine community is united in solemnly remembering those who perished, Western navies will be taking stock. The accident will likely have a knock-on effect on the Russian Navy’s massive modernization program. Most at risk is the submarine Belgorod.

On Sunday, a ceremony was held at the Serafimovsky Cemetery in Saint Petersburg. At the same time that a monument was being unveiled by Vice Admiral Igor Mukhametshin, Deputy Commander-in-Chief of the Russian Navy, the submarine was moored in Severodvinsk waiting for repairs to be completed.

The memorial is 650 miles south of where the accident happened, but close to the home of Russia’s secretive GUGI organization. GUGI stands for Main Directorate of Deep-Sea Research, and is seen as an espionage organization. Although the submarine is part of the Russian Navy, its mission is driven by GUGI.

The missions of these submarines is steeped in mystery and secrecy. It is the kind of thing that is only really discussed in euphemism by the defense community. They are referred to by terms like “seabed warfare” and “underwater engineering.” In layperson’s terms this means laying sensor networks on the sea floor, and possibly wire taps on internet cables. Losharik and the other ‘deep water stations,’ known as AGS, have manipulator arms so that they can work on cables on the sea floor. And they can dive to incredible depths, much deeper than regular submarines.

Although GUGI has a large submarine fleet, larger in fact than many leading navies and undoubtedly the largest fleet dedicated to spy missions, it is suffering from availability issues. Several of its submarines have been mothballed in the arctic city of Severodvinsk for many years. Right now, four of the deep diving midget submarines are there. These include Losharik, and that is a problem for the Russian Navy.

Losharik, which is formally known as AS-21, is the sole Project 10831 submarine. She is the most modern, and also the most capable, of the deep diving midget submarines. So she carried the greatest burden. And the newest of the special mission host submarines, Belgorod, is designed specifically to carry her.

Belgorod was launched on April 23, 2019, and is currently being fitted out in Severdovinsk. She is actually just across the river from where Losharik has most recently been seen. Belgorod is slated to be commissioned into the Russian fleet later this year, although that seems highly optimistic. And without Losharik available, there will be no meaningful ‘spy mission’ to test. Launch and recovery of Losharik will logically be a major phase of the testing. And Belgorod’s second mission, as a launch platform for the Poseidon strategic weapon, is not expected until 2027. This likely translates into a delay in Belgorod’s schedule.

We do not know how much longer Losharik’s repairs will take. The fact that she is in the water, being moved around Severodvinsk, may mean one of two things. Either there are delays in starting a phase of the work and she is waiting for a slot, or it is almost finished. You can be rest assured that analysts will be watching, trying to figure out what it all means for the Russian Navy. And your internet connection.

Russia’s spy submarine ‘Losharik’ is currently undergoing repairs in Severodvinsk. In this satellite image it can be seen moored outside a repair workshop. it was moved a few days later.

The Russia’s Secret Undersea Agenda

Few want to talk about how 14 sailors met their deaths on a Russian engineering marvel. Fewer still want to talk about what they were doing off Norway’s waters.

OFF THE COAST OF NORWAY — There could hardly have been a more terrifying place to fight a fire than in the belly of the Losharik, a mysterious deep-diving Russian submarine.

Something, it appears, had gone terribly wrong in the battery compartment as the sub made its way through Russian waters 250 miles north of the Arctic Circle on the First of July.

A fire on any submarine may be a mariner’s worst nightmare, but a fire on the Losharik was a threat of another order altogether. The vessel is able to dive far deeper than almost any other sub, but the feats of engineering that allow it do so may have helped seal the fate of the 14 sailors killed in the disaster.

The only thing more mysterious than what exactly went wrong that day is what the sub was doing in a thousand feet of water just 60 nautical miles east of Norway in the first place.

The extraordinary incident may offer yet another clue to Russia’s military ambitions in the deep sea, and how they figure into a plan to leverage Arctic naval power to achieve its strategic goals around the globe — including the ability to choke off vital international communication channels at will.

Moscow has been unforthcoming about the Losharik disaster, and insists that the sub was merely a research vessel. The Norwegian military, whose observation posts, navy and surveillance aircraft track Russia’s Northern Fleet for NATO, refuses to say what it may have seen. The only civilian witnesses to the rescue that followed the fire may have been a ragtag band of Russians fishing illegally in the area.

But it was clearly a mission of the highest sensitivity, and the roster of the dead included some of the most decorated and experienced officers of the Russian submarine corps.

To understand why these men may have found themselves on a submarine that can dive to perhaps 20,000 feet — more than 10 times deeper than crewed American subs are believed to operate — consider what crisscrosses the floor of the North Atlantic: endless miles of fiber-optic cables that carry a large fraction of the world’s internet traffic, including trillions of dollars in financial transactions. There are also cables linking the sonar listening devices that litter the ocean floor.

Russia’s president, Vladimir V. Putin, and his commanders have increasingly stressed the importance of controlling the flow of information to keep the upper hand in a conflict, said Katarzyna Zysk, head of the Center for Security Policy at the Norwegian Institute for Defense Studies in Oslo.

No matter where in the world a conflict might be brewing, cutting those undersea cables, Professor Zysk said, might force an adversary to think twice before risking an escalation of the dispute.

“The Russian understanding is that the level of unacceptable damage is much lower in Europe and the West than during the Cold War,” she said. “So you might not have to do too much.”

Not just any submarine can do that — at least, not across nearly the entire expanse of the sea bottom.

But the Losharik is not just any submarine. Its inner hull is thought to consist of a series of titanium spheres holding the control room, the bunks, the nuclear reactor and other equipment. Its name, it appears, was taken from an old Russian cartoon character, a horse assembled from small spheres.

The spheres are cramped, and they are joined by even smaller passageways.

A common procedure when there is a fire on a sub is to close the hatches to slow its spread. If that was done on the Losharik, the crew members may have found themselves trapped in small, dim, smoke-filled chambers.

And if they were in the chamber containing the battery compartment where the trouble appears to have started, they may have been battling flames raging in spaces as narrow as a couple of feet, said Peter Lobner, a former electrical officer on a United States submarine.

“That’s the creepiest place you ever want to be on a submarine,” Mr. Lobner said.

‘A Very Russian Story’

The Russian fishermen were out in a small boat, moving eastward, probably in restricted waters, when a submarine burst from the water in front of them, one later told a local newspaper in Murmansk, The SeverPost.

“We were heading towards Kildin,” a nearby island, the fisherman told a SeverPost reporter in a phone call, “and then, about half past nine in the evening, a submarine surfaces. Suddenly and completely surfaces. I have never seen anything like it in my life. On the deck, people were running around making a fuss.”

The submarine they saw was not the Losharik but a much larger vessel: its mothership. The Losharik is designed to fasten to its underside, so it can be carried along for servicing, transport over long distances or — as may have happened on July 1 off Norway — rescue.

Why Russia did not secure the area is unknown, but if the fisherman’s account is accurate, it appears they were the only outside witnesses to the secret rescue operation. They were fishing in a restricted area — but they decided to talk about what they saw anyway.

“This is a very Russian story,” said Jeffrey Mankoff, a senior fellow with the Russia and Eurasia Program at the Center for Strategic and International Studies in Washington.

The submarine sped away, but there was no immediate alert from Russia to the Norwegian Radiation and Nuclear Safety Authority about a possible nuclear incident in the Barents Sea, said Astrid Liland, head of the nuclear preparedness section.

TASS, the official Russian news agency, reported the accident the following day without mentioning that the submarine was nuclear powered. The SeverPost story appeared the next morning.

Russia and Norway, Ms. Liland said, have an agreement to notify each other in the case of incidents involving nuclear installations. “Unfortunately,” she said, “Russia interprets that agreement not to include military installations such as submarines.”

As convoluted as it is in so many ways, the tale of the Losharik, and the growing power of Russia’s Northern Fleet, begins with at least one very simple explanation, said Professor Zysk, the Norwegian analyst.

“There’s a special place in Putin’s heart for the navy,” she said. “That’s one of the key symbols of a great power.”

The Northern Fleet is at the top of Mr. Putin’s military budget, which included top-drawer items like the most advanced surface vessels and cruise missiles. In 2014, the Northern Fleet put the Arctic brigades under its command; soldiers equipped with the latest gear for cold climate warfare. New generations of ballistic-missile and attack submarines are also being deployed.

With all that naval power, the quickest way for Russia to surprise the United States would be to steam from the Arctic to the North Atlantic, said Heather A. Conley, senior vice president for Europe, Eurasia, and the Arctic at the Center for Strategic and International Studies.

“It’s really becoming a much more dynamic area,” Ms. Conley said. “It does feel like we’re updating ‘The Hunt for Red October.’”

There is also an eye toward economic benefit, Ms. Conley said: Russia has made no secret of its desire to control a northern shipping lane through the Arctic as ice recedes because of climate change and to expand its oil and gas production.

Over the last five years, 14 airfields have been opened or rebuilt along the Northern Sea Route; three fully autonomous bases have opened on Arctic archipelagoes. Billions of dollars have been spent on fields for gas production on the Yamal Peninsula, where total volumes are estimated at almost 17 trillion cubic meters. The natural gas from the Yamal will ultimately feed the pipeline now being built through the Baltic Sea to supply Western Europe.

Still, with the extreme difficulty of recovering oil and gas north of the Yamal, and the unknowns of tourism and foreign shipping, the economics may not add up for another half-century — if then, said Andreas Osthagen, a senior research fellow at the Fridtjof Nansen Institute, near Oslo, and author of “Coast Guards and Ocean Politics in the Arctic.”

Beyond Russia’s need to protect the nuclear deterrent itself, the key to understanding Russian’s keen interest in the Arctic, Professor Zysk said, is to bear in mind what Moscow does not want to do: become directly involved in any extended conflict with NATO. Russia knows it does not have the resources to win that kind of conflict, Professor Zysk said.

For that reason, no matter where a conflict begins, she said, “Russia would do anything to maintain the strategic initiative.” She said, “The information superiority comes here.”

Russian generals, for example, speak openly of sowing chaos in the government financial system of an adversary, Professor Zysk said, and disrupting seabed cables “would certainly fit into the objective.”

A 2017 report by Policy Exchange, a research and educational institute in the United Kingdom, found that seabed cables carry 97 percent of the data in communications globally, including roughly $10 trillion in financial transactions a day. The cables are largely unprotected and easy to find. As recently as a few years ago, American military and intelligence officials reported that Russian submarines had often been operating near them.

Because the internet can reroute data when cables are damaged, Western analysts have often dismissed the dangers of sabotage. But considering the vital role of data in Western institutions of all kinds, Professor Zysk said, simply applying pressure by degrading the network could be enough.

“When people lose Facebook and Twitter — oh, my God!” she said, not entirely facetiously.

Mathieu Boulègue, a research fellow in the Russia and Eurasia program at Chatham House, in the United Kingdom, said a specialized craft like the Losharik might help test the West’s ability to respond if cables were cut.

“This is part of Russia’s newfound capability of messing with us,” Mr. Boulègue said.

An Uncrackable Egg

As for the accident itself, few expressed surprise that a jewel of the Russian submarine fleet might catch fire not very far from its home base — probably in water no more than 1,000 feet deep — leaving most of its crew dead. The Russians, some experts said, seem to have a greater tolerance for risk than the West.

The Losharik was designed in the 1980s but, delayed by the fall of the Soviet Union, it was not launched until 2003, according to a forthcoming revised edition of “Cold War Submarines” by the historians Norman Polmar and K.J. Moore.

In 2012, the Losharik was part of a scientific operation to drill two miles into the Arctic crust and retrieve rock samples. The best public view of the sub came a few years later, in 2015, when it surfaced during a photo shoot of a Mercedes S.U.V. by the Russian edition of “Top Gear.”

Like the shell of an egg, the vessel’s titanium spheres resist terrific pressure much more readily than a traditional, elongated hull, Mr. Polmar said. “It can go slowly to the bottom and it won’t crack,” he said.

Mr. Polmar said there was “nothing in the U.S. fleet to match” the depths that the Losharik can take its crew. Various reports, he said, place the mysterious craft’s maximum depth at anywhere from 8,200 to 20,000 feet.

Mr. Lobner, the former American submarine officer, said “we have nothing except unmanned vehicles” operating at such depths.

Still, while some see an engineering marvel, others see evidence that Russia may be unable to build the kind of sophisticated, autonomous underwater drones the United States appears to rely on.

“They would rather adapt existing systems, modernize them, and try to muddle through,” Mr. Boulègue said. “So, no wonder these things keep exploding,” he said. Mr. Boulègue believes accidents have been far more common than publicly known.

John Pike, director of the think tank GlobalSecurity.org, said the Losharik fire suggested that the Russian military was still contending with some longstanding issues: corrupt contractors, and problems with quality control in manufacturing, spare parts supply chains and maintenance.

“I assume that every other sub in the Russian fleet has similar problems,” Mr. Pike said. “I just think the whole thing is held together with a lot of baling wire and spit.”

A Russian business newspaper, Kommersant, citing sources close to an investigation into the Losharik incident, said that when smoke was first detected in the sub, it did not appear to be catastrophic. The Losharik may have been docked with its mothership at the time, Kommersant said.

After a partial evacuation, 10 crew members stayed to fight the fire along with four reinforcements from the mothership, the situation became more and more dire as oxygen was depleted from two emergency breathing systems aboard the sub, Kommersant reported. The crew began succumbing to smoke inhalation, and there may have been an explosion in the battery compartment, the newspaper said.

Mr. Lobner said that even in an ordinary nuclear submarine, clearances in the battery compartment are so narrow that a routine inspection often requires shimmying through in a prone or supine position. The crew quarters would be small and could quickly fill with smoke, he said.

“This wouldn’t be like going into a burning house, ” Mr. Lobner said.

Eyes Open. Mouths Shut.

The Russians are not the only ones who don’t want to talk about the Losharik.

Adm. James G. Foggo III, commander of the United States Sixth Fleet, whose area of operations includes Europe, declined to be interviewed for this article. So did Haakon Bruun-Hanssen, chief of defense for the Norwegian Armed Forces.

Even Pvt. Sander Badar, a young conscript in the Norwegian Army, guarded his words carefully as he trained a pair of huge binoculars on the waters off Russia’s northern coast from his observation post on a ridge nearly a thousand feet above the Barents Sea. It was in that direction, on the other side of a stretch of coastline called the Fisherman’s Peninsula, that the Losharik burned.

“It’s not a secret that we are watching over their border and seeing what’s happening there,” Private Badar said early one October afternoon, the Arctic light already fading.

With outposts like Private Badar’s, as well as surveillance aircraft and navy ships, the Norwegian military serves as NATO’s eyes and ears on Russia’s doorstep. But when asked about Russian submarines, Private Badar declined to reveal what he may have seen.

When TASS, the Russian news agency, first reported the Losharik fire, it said 14 sailors had been killed aboard a “deep-sea station,” without mentioning its nuclear reactor. The next day, a spokesman for Mr. Putin said information on the accident “belongs to the category of top-secret data.”

In the following days, Mr. Putin posthumously conferred the nation’s highest honor, Hero of the Russian Federation, to four of the crew members and lesser awards to the other 10. At the funeral in St. Petersburg, a navy officer said the crew had “prevented a planetary catastrophe.” (A.R).