German authorities have arrested a Ukrainian national in Italy, a key breakthrough in the ongoing investigation into the 2022 sabotage of the Nord Stream natural gas pipelines, prosecutors announced Thursday, August 21.

The suspect, identified only as Serhii K. in accordance with German privacy laws, was detained near the Italian city of Rimini. Prosecutors said Serhii K. is believed to be a member of a group that planned the attack, planted explosives on the Nord Stream pipelines, and helped coordinate the attack. 

Following the arrest, the German Justice Ministry praised the "impressive success" of the overnight arrest, with Justice Minister Stefanie Hubig vowing to pursue the case until all suspects are in custody.

The arrest comes nearly two years after a series of underwater explosions in September 2022 ruptured three of the four Nord Stream pipelines in the Baltic Sea. The blasts, which occurred in Swedish and Danish waters, resulted in massive gas leaks and rendered the pipelines inoperable.

Although filled with gas, the pipelines were not operational at the time of the attack due to sanctions imposed on Russia following its full-scale invasion of Ukraine in February 2022. 

The Nord Stream 1 and 2 pipelines had long been a point of contention between Russia and Western nations, and the explosions were widely seen as an act of sabotage. So far, no one has claimed responsibility for the attack.

German authorities, who have led a joint investigation with Sweden and Denmark, issued an arrest warrant in August 2024 for a suspected ringleader, another Ukrainian national identified as Volodymyr Z. Officials said Volodymyr Z. had been living in Poland and chartered a German yacht to carry out the attack.