Erin Kelly

USA TODAY

WASHINGTON — Top U.S. intelligence officials told senators Thursday that they are confident in their assessment that Russia attempted to use cyberattacks to influence the U.S. presidential election, despite skepticism of their findings by President-elect Donald Trump.

"Our assessment now is even more resolute," Director of National Intelligence James Clapper told the Senate Armed Services Committee in testimony echoed by Adm. Michael Rogers, director of the National Security Agency.

Clapper said the intelligence community will release a public report next week detailing Russia's attempt to influence the U.S. presidential election by hacking Democrat Hillary Clinton's campaign and other political groups. The CIA and FBI have agreed that the interference was aimed at helping Trump beat Clinton.

Responding to questions from Democratic senators about Trump's criticism of the intelligence community, Clapper said he has no problem with elected officials having a healthy skepticism about information from the intelligence community, which he said is "not perfect" since it is made up of human beings.

However, Clapper added that "I think there is a difference between skepticism and disparagement."

"I do think that public trust and confidence in the intelligence community is crucial," he said. Clapper added that he has received many "expressions of concern" by U.S. allies "about what has been interpreted as disparagement of the Intelligence Community."

Trump has resolutely dismissed the intelligence community's claims about the Russians' involvement in the election. He is scheduled to be briefed Friday on the soon-to-be-released report on Russian hacking.

"The 'intelligence' briefing on so-called 'Russian hacking' was delayed until Friday, perhaps more time needed to build a case. Very strange!" the president-elect tweeted Tuesday.

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Sen. Lindsey Graham, R-S.C., reflecting the concern among some Republican lawmakers about Trump's rift with the intelligence community he will soon lead, said it's appropriate for Trump to challenge officials but not to undermine them.

"I think they need to be uplifted, not undermined," Graham said. "They're the best among us and they're trying to protect us."

Clapper told the committee that a comprehensive report ordered by President Obama on Russian hacking will be ready next week, including an unclassified version that the public will be able to review. He said lawmakers will receive closed-door briefings on the classified portions of the report. Obama received the report Thursday.

"Until then, I'm not really prepared to discuss this beyond our earlier statements," Clapper testified.

However, Clapper said the Russians had more than one motive in trying to interfere with the election, and the report will detail their multiple motives.

Clapper said the Russian interference "did not change any vote tallies or anything of that sort." He said there is no way for the intelligence community to gauge the impact of the hacking and the subsequent leak of information on how Americans voted.

Clapper said he intends to "push the envelope" to include as much information as he can in the public version of the report without compromising secret sources.

"I think the public should know as much as possible about this," he said.

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Armed Services Chairman John McCain, R-Ariz., warned Thursday that the U.S. must increase the punishment for cyber attacks by foreign nations.

"There is no escaping the fact that this committee meets today for the first time in this new Congress in the aftermath of an unprecedented attack on our democracy," he said, referring to the Russian hacks.

"The goal of this review, as I understand it, is not to question the outcome of the presidential election," McCain said. "Nor should it be. As both President Obama and President-elect Trump have said, our nation must move forward. But we must do so with full knowledge of the facts."

McCain said that the U.S. is too vulnerable to cyberattacks by foreign adversaries.

“What seems clear is that our adversaries have reached a common conclusion: that the reward for attacking America in cyberspace outweighs the risk," McCain said. "For years, cyberattacks on our nation have been met with indecision and inaction ... Unless we demonstrate that the costs of attacking the United States outweigh the perceived benefits, these cyber threats will only grow."

The U.S. intelligence community's conclusion that Russia hacked computers to tamper with the election led Obama to order sanctions against Russia last week, including the expulsion of 35 Russian “intelligence operatives" from the U.S.

Russia has denied any involvement in the hacking, accusing the Obama administration of attempting to disrupt U.S.-Russian relations. Wikileaks founder Julian Julian Assange has denied the information came from Russia, telling Fox News a "14-year-old" could have hacked into former Clinton campaign chairman John Podesta's emails. Clapper, responding to a question from McCain, said Thursday that he does not view Assange as a credible source.

"I don't think those of us in the Intelligence Community have a whole lot of respect for him," Clapper said of Assange.

Contributing: John Bacon and Gregory Korte