The US has imposed another round of sanctions over Russian hacking. 

The Treasury Department announced sanctions against five companies and three people on Monday, saying they'd help develop many of hacks coming out of Russia. 

The US is reacting to Russia-based cyberattacks, including the VPNFilter malware that infected more than half a million routers worldwide this year. Russian hacks have been tied to power outages in Ukraine and a ransomware attack that the US government called the "most destructive cyberattack in history." Hacks in the runup to the US presidential election in 2016 are also linked to Russia. 

Monday's sanctions take aim at cybersecurity companies and the people behind them for allegedly helping the Russian government develop hacking efforts.

"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. "Underwater" refers to Russian efforts to track undersea telecommunications cables.

The FSB, or Russia's Federal Security Service, is the successor to the KGB and is believed to carry out many of the government's cyberattacks. The FSB itself was sanctioned by the Treasury Department in 2016 and again earlier this year for cyberattacks.

The new sanctions block property under US jurisdiction belonging to the five companies and three people and also prevent them from making any transactions with "US persons."

The Treasury Department is sanctioning Digital Security, ERPScan and Embedi, three cybersecurity companies. While the latter two are not based in Russia, the department said they are owned by Russia-based Digital Security, which worked on a project to help Russia's hacking efforts. 

ERPScan and Embedi didn't respond to a request for comment.

The two other Russia-based companies are Kvant Scientific Research Institute and Divetechnoservices. The latter provides underwater equipment and diving systems to Russian agencies. The three Russians charged, Aleksandr Lvovich Tribun, Oleg Sergeyevich Chirikov, and Vladimir Yakovlevich Kaganskiy, all have worked for Divetechnoservices.

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