Intelligence officials and security analysts say Russian hackers are devoting much more effort toward implanting malicious software in the U.S. power grid than attempting to breach electoral systems, according to a new report.

Several intelligence officials told The New York Times that Russian efforts had been more focused on attacking and infiltrating U.S. infrastructure systems, while interference in electoral systems remained lower than the level witnessed in 2016.

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The report comes days after the Department of Homeland Security (DHS) reported that the scope of Russian intrusions was far greater than previously realized, and that Russian hackers gained access to the control rooms of power plants across the country.

“They got to the point where they could have thrown switches” said Jonathan Homer, chief of industrial control system analysis for DHS.

Missouri Sen. Claire McCaskill Claire Conner McCaskillMomentum growing among Republicans for Supreme Court vote before Election Day Democratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally MORE (D), who faces a tough reelection fight this year, told reporters this week that her office had been the victim of a Russian hacking attempt that Senate security staff had warned about earlier in the year.

“Russia continues to engage in cyber warfare against our democracy,” McCaskill said in a statement. “I will continue to speak out and press to hold them accountable. While this attack was not successful, it is outrageous that they think they can get away with this. I will not be intimidated. I’ve said it before and I will say it again, Putin is a thug and a bully.”

The Times report notes that one other Democratic lawmaker facing a reelection bid was targeted by Russian hackers, but the identity of the lawmaker has not been reported.

The White House said Friday in a statement that President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE had made clear that future Russian intrusions would not be tolerated, despite criticism that Trump has faced for his statement appearing to cast doubt on the intelligence community's assertion that Russian agents interfered in the 2016 election.

“The President has made it clear that his Administration will not tolerate foreign interference in our elections from any nation state or other malicious actors,” the statement said.