U.S. government officials have been notified of new cases of attempted or potentially successful cyber intrusions, CBS News has learned.

Officials would not go into specifics or reveal the number of new cases. But the revelation raises concerns that Russian cyberattacks have been more extensive than originally thought. Since the U.S released a report on election-related cyberattacks on Thursday, a government official said more cases have come to light, CBS News’ Justice and Homeland Security correspondent Jeff Pegues reports.

The intelligence information made public last week revealed some of the tools and infrastructure allegedly used by Russian hacking units. Those signatures were flagged over the weekend after officials connected with Vermont’s electric grid said malware code used in operation “Grizzly Steppe” was found on a Burlington Electric Department laptop.

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A team of Department of Homeland Security analysts has been working to determine if Russian hackers successfully breached Vermont’s system. But so far, investigators have not been able to determine the intent behind the Vermont incident, and there are no indications the power grid is compromised.

“While our analysis continues, we currently have no information that indicates that the power grid was penetrated in this cyber incident,” said Todd Breasseale, Department of Homeland Security Assistant Secretary for Public Affairs.

Late Monday night, The Washington Post reported that federal officials “are finding evidence that the incident is not linked to any Russian government effort to target or hack the utility, according to experts and officials close to the investigation.”

Monday’s revelation about new cases of attempted or potentially successful cyber intrusions came just days after the Obama administration announced a series of actions in response to what the White House called “the Russian government’s aggressive harassment of U.S. officials and cyber operations aimed at the U.S. election.” In addition to sanctions announced on Thursday, 35 Russian diplomats have been expelled from the United States.

While President Obama and most congressional Republicans have denounced Russia for its alleged election interference, President-elect Donald Trump has been reluctant to do so, even afterFBI Director James Comey and Director of National Intelligence James Clapper backed the CIA’s judgment that Russia interfered. The CIA said in December it has high confidence that Russians tried to influence the election and that they favored Mr. Trump.

“I know a lot about hacking,” Mr. Trump said before his New Years Eve party at Mar-a-Lago Saturday night. “And hacking is a very hard thing to prove. So it could be somebody else. And also - I know things that other people don’t know - and so they cannot be sure of the situation.”

Mr. Trump promised new information on Tuesday or Wednesday. But Sean Spicer, the Trump transition’s spokesman, seemed to walk that back.

“Well it’s not a question of necessarily revealing, remember the president-elect is privy to a lot of classified information, intelligence reports, he gets briefed by his national security team on a daily basis,” Spicer said, speaking on CNN.

It is unclear, however, where Mr. Trump or his national security team are getting their intelligence reports. All U.S. intelligence agencies are in agreement that the Russian government with the blessing of Russian President Vladimir Putin orchestrated “aggressive” cyberattacks prior to and during the U.S. election.