Russia said it was "possible" for its power grid to be the subject of a cyber attack by the United States.
Kremlin spokesman Dmitry Peskov said US cyber-warriors have put computer viruses on his power grid, a "hypothetical possibility."
His comments came in response to a New York Times (NYT) article stating that US hackers were targeting Russian power plants.
The report sparked expert skepticism and a denunciation from President Trump.
In its report, the newspaper said that the "code" American had been deployed in many elements of the Russian energy network.
The Times said it was an escalation of work done by the United States to combat Russian misinformation and hacking campaigns.
Mr. Peskov said that President Trump had rejected the allegations made in the Times, calling them "fake news".
The Kremlin spokesman added: "If it is assumed that some government agencies do so without informing the head of state, this can of course indicate that the cyber war against Russia could be a possible hypothesis ".
He said that "vital sectors" of the Russian economy were continually attacked, but that it had succeeded in countering intrusions and not causing damage.
The New York Times story was challenged by Thomas Rid, a political scientist at the Johns Hopkins School of International Studies, who said: does not make sense because "advertising burns capabilities".
The story will encourage Russia to search for as many malicious code on its power grid, he said, making it likely that the virus will be found.
He added that the Russian power grid is vast and "extremely complex", preventing cyber-attackers from entering and leaving viruses in place for a long time.
The malicious code was allegedly inserted by US Cyber Command soldiers. This group of military pirates is allowed to conduct a "clandestine military activity" on computer networks under the National Defense Authorization Act, passed in 2018.
The United States has been probing Russian electrical systems since 2012, the NYT reported, but were now more interested in finding weaknesses and inserting viruses.