Washington (CNN) The US is escalating cyber attacks on Russia's electric power grid and has placed potentially crippling malware inside the Russian system, The New York Times reported Saturday.

The placement of the malware that deep within the Russian grid had never previously been attempted, the Times reports, and is intended partly as a warning and also to put the US in a position to conduct cyber attacks should a significant conflict arise with Russia.

Two administration officials told the Times they believed President Donald Trump had not been briefed in any detail about the US computer code being implanted inside the Russian grid.

Pentagon and intelligence officials describe to the Times "broad hesitation" to tell Trump about the details of the operations against Russia. They tell the Times there was concern over how Trump would react, and the possibility that Trump might reverse the operations or discuss it with foreign officials.

Trump said in a string of tweets Saturday evening that the Times report was "NOT TRUE," calling the Times' reporting "a virtual act of Treason" and the news media the " enemy of the people ."

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