Intelligence agencies and investigators across Europe will now be trying to figure out what caused the explosions. In addition to 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, this is likely to involve more than one step.

Nord Stream 1 was paused for repairs in August andNord Stream 2 wasn't officially opened until February, but both pipes are holding gas There were three leaks in the Baltic sea. Germany and Poland are located to the south of the island. The leaks are in international waters, but also in the exclusive economic zones of both Danes and Swedes. The average depth in this region is around 50 meters.

According to security sources, the attacks could have been carried out by underwater drones, mines being dropped or planted by boats, or even from within the pipes themselves. We don't know if they came from the outside or the inside of the line. Cleaning and inspection machines can be sent from Russia to Germany. Pigging could have been used to carry out an attack.

A review of the project by the Swedish Defence Research Agency warned about the risk of explosions around the pipe. The report said that a single diver would be enough to set an explosion. The impact of such an assault would be rather modest and most likely a minor incident of this type would not result in a big explosion.

Russia has the ability to conduct warfare with divers and mini-submarines. Confirmation of any responsibility isn't easy. The shallow depth of the area around theNord Stream pipes makes it unlikely that a large submarine would be operating nearby.

It is possible that other vessels could have caused the damage. It is not clear where any of the systems are. It is not the case that all of the Baltic Sea is filled with sensors. It's not possible to know at every time what's happening on the surface and on the seabed.