Italian authorities, on 20/8, executed an arrest warrant issued by German prosecutors for Serhii K., a former Ukrainian army officer suspected of leading the group that sabotaged the Nord Stream pipeline in 2022.

German police identified Serhii K. as the head of a 6-person group, including 4 civilian divers, secretly recruited by a special unit of the Ukrainian army to plant explosives that damaged the Nord Stream 1 and Nord Stream 2 pipelines under the Baltic Sea in 9/2022.

The arrest of Serhii K. is a significant breakthrough in the international investigation to track down the suspects accused of carrying out the attack, considered one of the largest acts of sabotage in modern times.

Gas leak from the Nord Stream 1 pipeline in Sweden's exclusive economic zone in the Baltic Sea in 9/2022. Photo: Reuters

Gas leak from the Nord Stream 1 pipeline in Sweden's exclusive economic zone in the Baltic Sea in 9/2022. Photo: Reuters

The Nord Stream pipeline system, consisting of Nord Stream 1 and Nord Stream 2, transported gas from Russia to Europe, generating billions of USD in profit for Moscow each year before the Ukraine conflict erupted in 2/2022.

Early on the morning of 26/9/2022, Scandinavian seismologists detected underwater tremors near the island of Bornholm, Denmark. These were the result of three powerful explosions when the two Nord Stream pipelines were bombed, releasing the largest amount of gas ever recorded, equivalent to Denmark's annual CO2 emissions.

The incident exacerbated the energy crisis in Europe. Denmark, along with Sweden and Germany, the three countries closest to the scene, then opened investigations and concluded it was an act of sabotage. Initial suspicions fell on Russia, but subsequent investigations gradually revealed the role of a group of Ukrainians.

An investigation by the Wall Street Journal in 8/2024 revealed that the plan to attack the Nord Stream pipeline was formed in 5/2022 when senior Ukrainian officers and businessmen gathered at a pub in Kyiv to celebrate Ukraine's success in halting Russia's advance.

They believed that sabotaging the pipeline, a vital source of revenue for Moscow, was the most effective way to make Russia pay for its attack on Ukraine. At the same time, German investigators collected evidence including emails, mobile phone and satellite phone data, as well as fingerprints and DNA samples from the group accused of sabotaging the pipeline.

Those involved said the sabotage plan, internally codenamed "Operation Diameter," cost Ukraine about 300,000 USD. A general experienced in special operations oversaw the mission and reported directly to the then-head of the Ukrainian armed forces, Commander-in-Chief Valery Zaluzhny. Zaluzhny was later appointed ambassador to the UK and denied any involvement in the operation.

Former Commander-in-Chief of the Ukrainian Armed Forces, General Valeriy Zaluzhniy. Photo: AFP

Former Commander-in-Chief of the Ukrainian Armed Forces, General Valeriy Zaluzhniy. Photo: AFP

The operation commanders then recruited a 6-person team to carry out the bombing: Serhii K., a woman in her thirties with diving expertise, and four experienced deep-sea divers.

"Serhii K. was a link in the group that planted explosives on the Nord Stream 1 and Nord Stream 2 gas pipelines," the German federal prosecutor's office said on 21/8.

Captain Serhii K. allegedly served in the Security Service of Ukraine (SBU) and an elite unit that defended Kyiv in the early months of the conflict with Russia. According to Ukrainian sources, he was recruited for "Operation Diameter" in 5/2022.

German prosecutors say Serhii K. coordinated the field operation. Along with accomplices, he allegedly rented a 15-meter yacht named Andromedain in the German port town of Rostock. The boat was rented through intermediaries using forged identity documents, and Serhii K. handled these arrangements.

Equipped only with diving equipment, satellite navigation, handheld sonar, and open-source seabed maps marking the location of the pipelines, the 6-person team set off. However, bad weather forced them to postpone the mission and stop at the port of Sandhamn, Sweden. The group discussed whether to abort the mission, but the storm later subsided.

According to a source familiar with the German investigation, upon arrival, the four divers split into two pairs, taking turns diving to plant bombs on the pipelines near the Danish island of Bornholm.

Operating in icy, pitch-black waters, they used a powerful explosive known as HMX, connecting it to timers. HMX is so potent that a small amount is enough to tear apart high-pressure pipelines on the seabed, causing huge bubbles to rise to the surface.

According to several extensive media investigations, including by the German magazine Der Spiegel, those familiar with the plan said the Ukrainian commanders behind it did not think they had committed a crime. They viewed it as a legitimate attack on a military target after Russia launched its campaign in Ukraine, partly because the profits from supplying gas to Germany contributed significantly to funding the Russian military.

Der Spiegel's investigation uncovered evidence suggesting the group's actions were punished by the Ukrainian armed forces, although Kyiv denies involvement.

German prosecutors issued international arrest warrants for Serhii K. and other suspects earlier this year, following a nearly three-year investigation into the sabotage.

According to German prosecutors and Italian police, after collecting data, German investigators monitored Serhii K. in Ukraine. Discovering that he was moving his wife and two children from Ukraine to Poland en route to Italy, German authorities acted swiftly.

When the suspect and his family arrived in northern Italy on 18/8, German police issued an arrest warrant and notified Italian authorities. The suspect's family then moved to the village of San Clemente on the Adriatic coast. There, he used his passport to register his accommodation.

Italian police immediately dispatched Carabinieri officers to arrest Serhii K. near San Clemente on the night of 20/8 as he and his son were heading to a local university. The man did not resist arrest.

Italian authorities must extradite the suspect to Germany, where the arrest warrant was issued, in the coming days. Sources familiar with the investigation say that if convicted, Serhii K. could face up to 15 years in prison but could receive a reduced sentence for cooperating with the prosecutor.

Last year, German police issued an arrest warrant for another man, Volodymyr Z., a Ukrainian diver living in Poland, suspected of being part of the group that sabotaged the Nord Stream pipeline. However, Polish authorities failed to execute the warrant in time, and Volodymyr Z. managed to return to Ukraine.

The Nord Stream pipelines were sanctioned last month by the European Union (EU) as a way to pressure Russia over its campaign in Ukraine.

Nord Stream 1 became operational in 2011, and Nord Stream 2 was completed in late 2021 but never operated. During construction, these pipelines sparked major controversy in both Europe and the US. The US criticized Germany for helping build the pipelines because they increased Europe's dependence on Russian gas.

The Nord Stream pipelines were once one of Europe's most important energy arteries and the world's largest offshore gas infrastructure. It was designed to supply up to 110 billion cubic meters annually for at least half a century.

Leak locations after the explosions on the Nord Stream 1 and Nord Stream 2 pipelines in 9/2022. Graphic: Guardian

Leak locations after the explosions on the Nord Stream 1 and Nord Stream 2 pipelines in 9/2022. Graphic: Guardian

No one was killed or injured in the 2022 Nord Stream pipeline sabotage. The incident left Moscow with only one main route to transport gas to Europe: through pipelines across Ukrainian territory. Despite the conflict, until 1/2025, Ukraine still collected transit fees for Russian oil and gas, estimated to be worth hundreds of millions of USD annually.

German Justice Minister Stefanie Hubig said the arrest of suspect Serhii K. was an "impressive success" for German prosecutors. She called for a thorough resolution of the incident, including from a criminal law perspective.

Vu Hoang (According to WSJ, Al Jazeera, Guardian)