WASHINGTON – The U.S. Treasury imposed sanctions on three Russian individuals and five firms on Monday, saying they had worked with Moscow’s main intelligence service on ways to conduct cyber attacks against the United States and its allies.

“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 T. Mnuchin said in a statement, using an acronym for the Russian Federal Security Services.

The designation allows the United States to block all property and interests belonging to the individuals that are subject to U.S. jurisdiction.

Russia’s “malign and destabilizing cyber activities” included the NotPetya attack last year that spread across Europe, Asia and the Americas, attacks on the U.S. energy grid and on network infrastructure including routers and switches, the Treasury statement said.

“Today’s action also targets the Russian government’s underwater capabilities,” it said. “Russia has been active in tracking undersea communication cables, which carry the bulk of the world’s telecommunications data.”

The designated firms are Digital Security, ERPScan, Embedi, Kvant Scientific Research Institute, Divetechnoservices. The individuals named on Monday all had ties to Divetechnoservices: Aleksandr Lvovich Tribun, Oleg Sergeyevich Chirikov and Vladimir Yakovlevich Kaganskiy.