Investigators across Europe, including intelligence agencies, will now be trying to piece together exactly who and what caused the apparent explosions. This is likely to involve multiple steps, such as examining what data is held about the area, including seismic data and other sensors, checking whether any communications around the incident have been intercepted, and examining the pipelines to see if there are any signs of intentional destruction.
Neither of the pipes is operational—Nord Stream 1 was paused for repairs in August and Nord Stream 2 has not officially opened after Germany pulled support for it ahead of Russia’s full-scale invasion of Ukraine in late February—but both pipes are holding gas. All three leaks happened relatively close to each other, near the Danish island of Bornholm, in the Baltic sea. The island is surrounded by Denmark to the west, Sweden to the north, and both Germany and Poland to the south. The leaks are in international waters, but also sit in both Denmark and Sweden’s exclusive economic zones. “It’s quite shallow, around 50 meters on average in this region,” says Julian Pawlak, a research associate at the Helmut Schmidt University and the German Institute for Defence and Strategic Studies.
Security sources have speculated if the attacks were deliberate, they could have been conducted by unmanned underwater drones, involve mines being dropped or planted by boats, been carried out by divers, or even from within the pipes themselves. “We still don’t know what the origin is of those explosions or where they came from—if they originated from the outside or if they originated from the inside of the pipelines,” Pawlak says. In a process called “pigging,” cleaning and inspection machines can be sent down the pipes from Russia in the direction of Germany. It’s possible pigging was repurposed to carry out an attack.
Back in 2007, before the first Nord Stream pipeline was constructed, a review of the project by the Swedish Defence Research Agency (FOI) warned about potential explosions around the pipe, in the context of terrorism. “Despite its concrete coating, a pipeline is rather vulnerable, and one diver would be enough to set an explosive device,” its report said. “However, the impact of such an assault would probably be rather modest and most likely a minor incident of this type would not result in a large explosion.”
“They [Russia] have the capability for subsea warfare, with the divers, but also with mini-submarines and drones,” Hansen says. However, confirming any responsibility isn’t necessarily straightforward. The relatively shallow depth of the area around the Nord Stream pipes means it is unlikely that any large submarines would have been operating nearby, as they would be easy to detect.
Pawlak says any vessels in the area could potentially detect others that may have caused the damage. Undersea sensors could equally spot something in the area moving, but it is unclear where any of these systems are. “It’s still not the case that all of the Baltic Sea is filled up with sensors and that NATO knows every movement,” Pawlak says. “On the surface, but especially on the seabed, it’s still not possible to know, at every time, at every place, what’s moving, what’s going on.”
