The United States treasury announced on Monday that it was implementing new sanctions on three Russian individuals and five Russia-based firms, alleging that they were responsible for a series of cyber attacks carried out against the United States and its allies. These attacks, which the treasury asserts were conducted under the purview of Moscow’s intelligence service, include hacking into the United States’ energy grid.

“The United States is committed to aggressively targeting any entity or individual working at the direction of the FSB whose work threatens the United States and will continue to utilize our sanctions authorities, including those provided under CAATSA, to counter the constantly evolving threats emanating from Russia,” Treasury Secretary Steven Mnuchin said in written statement on Monday.

This most recent statement echoes similar ones made by Mnuchin in March, when the U.S. Government first formally acknowledged Russia’s success at infiltrating the American energy grid while implementing a round of sanctions on others that were allegedly involved in the endeavor. According to officials at the time, the infiltration was detected and “removed from the system,” but it can be difficult to overstate the threat posed by Russia’s ability to hack into America’s national electrical infrastructure. Experts have estimated that as much as 90% of the U.S. population would die within two years of a permanent national blackout. In more immediate terms, the vast majority of the country’s military bases, law enforcement, and intelligence community rely on commercially sourced power.

With very few long-term redundancies in place, America’s defensive infrastructure would be significantly undermined by even intermittent issues with the national energy grid. Satellite communications depend on ground based transmission and reception equipment and a great deal of land-based communications between defensive assets are carried over the same means as public communications. Without electricity, the nation would be hard pressed to mount a significant response to an impending threat.

In November, well before the United States acknowledged its awareness that Russia had managed to gain access to the electrical grid, Lucian Niemeyer, assistant secretary of defense for energy, installations and environment spoke to Congress about how far the nation is from having a legitimate solution to the Defense Department’s reliance on publicly sourced power. Niemeyer said,

We’re here to find out what the most efficient and effective way we can get toward providing resilient power, [and] to provide redundant power to be able to allow us to continue to operate in case something happens to the grid, it’s not something that can happen in a year.”

The sanctions aren’t only a result of this looming threat however — other cyber attacks, including the NotPetya cyber attack that spread like wildfire across Europe, Asia and the Americas last year, and perhaps even more troubling, Russia’s apparent efforts to meddle with undersea communication cables.

The Treasury statement said,