Russian forces have encountered operational problems and a decline in assault activity along parts of the frontline after unregistered Starlink satellite internet terminals used by Moscow’s troops were blocked, a source in Ukraine’s armed forces told Interfax-Ukraine.

The source in the General Staff of the Armed Forces of Ukraine said the shutdown had negatively affected Russian communications and command and control, leading to fewer attacks in some areas. Ukrainian officials say Starlink terminals have been widely used by both sides in the war for battlefield connectivity.

Russian troops reported mass disruptions to their terminals on February 5, complaining that the loss of connectivity would hamper coordination along the frontline.

Serhiy Beskrestnov, an adviser to Ukraine’s defence minister known by the call sign “Flash”, said Russian units had “lost all control” after the blocking and that assault operations had stopped in many directions. He added that Ukrainian units faced issues only where their terminals had not been registered in time under a newly introduced “white list” verification process.

Ukraine’s defence minister, Mykhailo Fedorov, confirmed that Starlink terminals used by Russian forces had been blocked and said the registration of Ukrainian terminals was continuing. He had earlier announced the launch of a nationwide verification process.

The move drew a public reaction from Polish Foreign Minister Radoslaw Sikorski, who thanked billionaire Elon Musk, whose SpaceX company operates Starlink, for the shutdown. “Better late than never. Thank you, Elon Musk,” Sikorski wrote on X, commenting on reports by Russian military bloggers of widespread outages.

The exchange follows a public dispute in late January, when Sikorski urged Musk to stop Russian forces using Starlink.