Russia's naval activity near undersea cables is reportedly drawing the scrutiny of US officials, further sparking concerns that the Kremlin may be plotting to "sabotage" underwater infrastructure via a secretive, dedicated military unit called the General Staff Main Directorate for Deep Sea Research (GUGI).

"We are concerned about heightened Russian naval activity worldwide and that Russia's decision calculus for damaging US and allied undersea critical infrastructure may be changing," a US official told CNN in an exclusive report. "Russia is continuing to develop naval capabilities for undersea sabotage mainly thru GUGI, a closely guarded unit that operates surface vessels, submarines and naval drones."

CNN, citing two US officials, reported that Russian ships have been spotted near critical deep-sea cables and infrastructure far away from that country's shores.