Suspicions Multiply as Nord Stream Sabotage Remains Unsolved

Russian and Danish naval vessels that disappear in the Baltic Sea, days before an underwater pipeline blast. A German charter yacht with traces of explosives, and a crew with forged passports. Blurry photographs of a mysterious object found near a single surviving pipeline strand.

These are the latest clues in the hunt to reveal who, last Sept. 26, blew up most of the Kremlin-backed Nord Stream pipelines, some 260 feet below the Baltic Sea, that were once the largest supplier of Europe’s natural gas.

Just a few weeks ago, New York Times reporting on new intelligence, along with German police findings reported by the German media, suggested a possible solution to the Nord Stream puzzle: pro-Ukraine operatives renting a German pleasure boat and pulling off a fantastical covert mission.

Since then, a flurry of new findings and competing narratives has sown distrust among Western allies and presented an opening for Russian diplomatic pressure that has raised the geopolitical stakes in Europe’s Baltic region.

Nowhere is the tension felt more strongly than among the 98 residents of Denmark’s Christianso — an island so tiny, you can walk across it in 10 minutes. Living just 12 nautical miles away from the blast site, everyone from the herring pickler to the inn chef sees skies and waters filled with foreboding.

“Before the blast, no one talked about Nord Stream. I didn’t even know how close we were until it happened,” said Soren Thiim Andersen, governor of Christianso. “Afterward, we all felt exposed. We were all wondering: What really just happened here?”

The pleasure boat at the center of the German investigation, the Andromeda, docked at Christianso’s stone harbor after being chartered in the northern German port of Rostock on Sept. 5 and making an overnight stop at Wiek, a more obscure north German port with no security cameras and little oversight.

A local port worker, who asked not to be identified because of ongoing investigations, told The Times that he remembered the visit unusually well: He had repeatedly tried to speak to the crew, first in German, then English. Instead of attempting any kind of reply, in any language, one man simply handed him the docking fee and turned away.

The Andromeda now sits in dry dock overlooking the Baltic Sea, its innards pulled out by investigators. Three German officials told The Times that the investigators had found traces of explosives on the boat, and discovered that two crew members had used fake Bulgarian passports.

That hunt led back to Christianso, where Mr. Andersen, the governor, said that in December, the Danish police had him write a Facebook post, instructing residents to send photographs of the harbor or boats from Sept. 16 to Sept. 18, around the time the Andromeda is believed to have docked. Investigators arrived a month later to interview residents and check the photos.

Christianso locals scoffed at the idea a 50-foot pleasure yacht could pull off such a spectacular attack — and so have naval experts from Germany, Sweden and Denmark.

They argue that even with skilled divers, it would be extremely challenging for a six-person crew to plant the explosives needed on the seabed some 262 feet below, and create blasts registering 2.5 on the Richter scale.

“Knowing how the explosion would work, with the sea pressure at those depths — you need very specialized knowledge. How do the physics play out?” said Johannes Riber, a naval officer and analyst at Denmark’s Institute for Strategy and War Studies, who called it a “James Bond” theory.

Whether the Andromeda was a decoy or part of a broader mission, he said, remained unanswerable. But the most plausible attack, he said, required an undersea drone or mini submarine to plant the explosives, and either naval or professional underwater drilling vessels.

Mr. Riber and others also pointed to photographs of the aftermath — pipes bent backward, cracks and craters on the seabed — as traces of a massive bomb, something in the range of 1,000 to 1,500 kilograms.

“This was not a few pieces of plastic explosives,” Mr. Riber said. “That is a powerful explosion at play.”

Yet one pipeline expert and a professional diver who was part of the team that laid the Nord Stream 2 pipelines last year disagreed. Both the expert and the diver, who works regularly in the Baltic Sea, insisted a small plastic explosive could do the job, as long as it was placed near a seam of the pipeline. They asked not to be identified because they were speaking without authorization from Nord Stream.

“It is like lighting a match next to a leaking gasoline pump — the gas is all you need,” said one diver.

By the end of March, Russian diplomats threw up yet another twist: They revealed that in February, Nord Stream 2 had hired a vessel to inspect its pipelines and discovered an unidentified object next to a seam of its sole undamaged strand, about 19 miles from the explosion sites. The company alerted both Russia and Denmark, which controls the waters in which the object was spotted.

Even under pressure from Vladimir V. Putin’s top foreign policy adviser, who summoned Denmark’s chargé d’affaires in Moscow, Denmark initially resisted offering much information to the company or Russia, aside from publicly releasing a blurry photo of a 12-inch-long cylinder, covered in algae.

Last week, Danish authorities allowed Nord Stream 2 to observe their dive to recover the object — releasing photographs of a now cleaned-off dark cylinder. Denmark’s ministry of defense said it might be part of a maritime smoke buoy.

But Russia’s ambassador to Denmark, Vladimir Barbin, told The Times that experts in Moscow believed the cylinder was part of an explosive device.

“The continued secrecy of the ongoing investigation by Denmark, Germany and Sweden, as well as the refusal to cooperate with Russia, undermine its credibility,” Mr. Barbin wrote in a statement to The Times.

And Mr. Putin himself continues to use the incident to pressure Denmark to back Moscow’s demands for a joint international investigation. On April 5, he warned the situation in the Baltic Sea was becoming “turbulent in a literal sense.”

Even as Moscow pushes for a joint probe, other findings are pointing fingers back at Russia.

The German news website T-Online worked in late March with an open-source investigator, Oliver Alexander, to present the paths of six Russian vessels whose names were given to them by what they described as an “intelligence source from a NATO country.”

Their findings showed the boats disappeared from satellite signals on Sept. 21 — around the time Christianso residents spotted vessels that disappeared from their apps — after veering off course from a publicly announced Russian maritime exercise.

That information could match an early lead that one German official told The Times was explored late last year by Germany’s intelligence services who had also tracked Russian vessels from naval exercises, but were unable to bridge an approximately 20-nautical-mile gap between where some veered off course and the sites of the blasts.

The open source investigation also discovered a Danish naval ship, the Nymfen, which had sailed toward the same area as the Russian vessels in the hours after they disappeared. It too had turned off its signal upon reaching the site.

A day later, a Swedish fighter jet took an unusual flight path over the area, followed by a Swedish naval vessel that lingered near the spot where the Nord Stream 1 pipelines later exploded.

The researchers argued that perhaps these forces went to check the site — hinting that some countries may know more than they have said thus far.

Denmark is the most tight-lipped, but security sources who spoke on condition of anonymity told The Times that Danish and Swedish investigators have been wary of the latest German findings, and feel a sense of pressure to counter that narrative.

On Thursday, Mats Ljungqvist, Sweden’s senior prosecutor in the case, told the Swedish newspaper Norrkopings Tidningar that although his probe had not ruled out nonstate actors, only a “very few companies or groups” could have done it, and that a state actor still seemed most likely.

And he hinted his team came across some red herrings in the course of their investigation: “Those who carried this out were careful with the traces they left behind,” he said.

Privately, Swedish, German, and Danish officials argued that investigators have reasons not to share findings, which can reveal their intelligence capabilities. Allies have also grown wary after a string of Russian espionage and infiltration cases in Europe — including one within Germany’s spy agency.

Nor may it be in anyone’s interest to share: Naming a culprit could set off unintended consequences.

Claiming Russia was behind the attack would mean it had successfully sabotaged major critical infrastructure in Western Europe’s backyard, and could spark demands for a response.

Blaming Ukrainian operatives could stoke internal debate in Europe about support for their eastern neighbor.

And naming a Western nation or operatives could trigger deep mistrust when the West is struggling to maintain a united front.

“Is there any interest from the authorities to come out and say who did this? There are strategic reasons for not revealing who did it,” said Jens Wenzel Kristoffersen, a Danish naval commander and military expert at the University of Copenhagen. “As long as they don’t come out with anything substantial, then we are left in the dark on all this — as it should be.”

Reporting was contributed by Christopher F. Schuetze in Berlin, Jasmina Nielsen in Copenhagen and Christina Anderson in Stockholm.