The US has detected increased Russian military activity around key undersea cables and believes Russia is likely to engage in sabotage operations aimed at disabling a critical part of the world’s communications infrastructure, two US officials told CNN.

Russia has created a special military unit that has deployed a formidable fleet of surface ships, submarines and naval drones, according to one of the officials. The unit, the “Main Directorate General of Staff for Deep Sea Research”, she is known by her Russian acronym GUGI.

“We are concerned about increased Russian naval activity worldwide and the possibility that Russia has decided to destroy vital US and allied undersea infrastructure,” a US official told CNN. “Russia continues to develop naval capabilities for submarine sabotage primarily through its GUGIa closely guarded unit that uses surface ships, submarines and naval drones.”

At the same time that the White House directly accuses Moscow of trying to influence the US election of Nov. 5, the U.S. routinely monitors Russian ships that patrol near critical marine infrastructure and undersea cables often far from Russian shores, the official said. US concern about the undersea operations of the secretive Russian unit has not been reported before.

Undersea cables form a critical backbone for the operation of the Internet and telecommunications around the world. Most communications and the operation of the Internet is carried out over a vast network of high-speed fiber optic cables laid along the ocean floor. A coordinated attack could significantly disrupt private, government, and military communications. It would also affect industries that rely on such communications, including financial markets and energy suppliers.

Undersea cables also carry huge amounts of electricity to many European countries. The US and its allies closely monitor Russian naval activity through key undersea cables around the world. NATO commanders conducting patrols in the area in April 2023 told the CNN that they had seen an increase in specific activity on submarine cables in the Baltic Sea in recent years.

The seas around the Northern Europe they are the focus of Russian military surveillance and activity. Last year, a joint investigation by the public broadcasters of Sweden, Denmark, Norway and Finland found that Russia has a fleet of suspected spy ships operating in northern European waters to potentially sabotage both submarine cables and wind farms.

Using data analysis, intercepted radio communications, and intelligence sources, the broadcasters monitored for several years about fifty ships operating in the area, using underwater surveillance to map locations for potential attacks.

Taiwanese and US forces have detected similar activity by the Chinese navy in waters around Taiwan. “The activity looks like targeted harassment by Beijing – or an exercise in preparation for cutting off all of Taiwan,” Elisabeth Braw wrote in Foreign Policy magazine in February 2023.

Russia’s threat activity has not been disrupted by the ongoing war against Ukraine. The Russian leadership places great value on GUGI, a US official told CNN, which continues to fund the unit even as it wages war in Ukraine.

A US official told CNN that the US would view any such sabotage of undersea infrastructure as a significant escalation of Russian aggression outside of Ukraine.

“Any activities that would destroy infrastructure on the seabed, including undersea cables, especially during times of heightened tension, would lead to an unintended escalation,” the US official told CNN. “The US would be particularly concerned about damage to our or our allies’ critical undersea infrastructure.”