The Treasury Department on Monday imposed new sanctions against Russian businesses and individuals linked to the Kremlin’s main security agency over their role in cyberattacks against the U.S.

The sanctions are the latest in a series of escalating actions from the Trump administration intended to punish Russian entities involved in cyberattacks targeting the U.S. energy grid, as well as the global malware attack NotPetya last year, among others.

“The entities designated today have directly contributed to improving Russia’s cyber and underwater capabilities through their work with the FSB and therefore jeopardize the safety and security of the United States and our allies,” Treasury secretary Steven Mnuchin said in a statement.

The U.S. imposed sanctions on five entities: Digital Security, ERPScan, Embedi, Kvant Scientific Research Institute and Divetechnoservices. Sanctions were also levied on three individuals: Aleksandr Lvovich Tribun, Oleg Sergeyevich Chirikov and Vladimir Yakovlevich Kaganskiy.

The sanctions block access to any property the people or companies that are in U.S. jurisdiction, and prohibit U.S. citizens from any transactions with them.

Treasury said that Monday’s action “targets the Russian government’s underwater capabilities.”

“Russia has been active in tracking undersea communication cables, which carry the bulk of the world’s telecommunications data,” the agency said.