Evan Vucci/AP

Intelligence agency leaders repeated their determination Thursday that only “the senior most officials” in Russia could have authorized recent hacks into the U.S. electoral and political system.

The director of National Intelligence, James Clapper, affirmed an Oct. 7 joint statement from 17 intelligence agencies that the Russian government directed the election interference — and went further.

“We stand more resolutely on that statement,” Clapper said during a Senate Armed Services hearing with the intelligence chiefs into the politically charged issue.

Clapper noted that the intelligence officials would not dive into many more details at this hearing, deferring to a broader, unclassified report on the election interference to be released next week.

Committee Chairman Arizona Republican John McCain said there is no national security interest “more vital to the U.S. than the ability to hold free and fair elections without foreign interference,” and that “every American should be alarmed by Russia’s attacks on our nation.”

“We will ascribe” a motive for the Russian cyber attack in the upcoming report, Clapper said. He wouldn’t say Thursday what it is, but it has been widely reported that the intelligence agencies agree that Russia was trying to get Donald Trump elected.

Clapper also said he will “push the envelope” to make much of that report unclassified without jeopardizing sources or intelligence-gathering details.

“The public should know as much about this as possible,” Clapper said.

In addition to Clapper, testifying before the committee were Defense Undersecretary Marcel Lettre and Adm. Michael Rogers, commander of the U.S. Cyber Command of the National Security Agency. All three will be leaving their positions at the end of the Obama administration.

One of the first questions from McCain was about the involvement of Julian Assange, the founder of Wikileaks, which published emails the intelligence community says were hacked by the Russians of Hillary Clinton’s campaign manager John Podesta.

Assange has denied the Russian government gave Wikileaks the emails. McCain asked Clapper if Assange had any credibility.

“Not in my view,” Clapper said.

President-elect Trump, however, has openly questioned whether Russia was involved in the hacking, pointed to errors the intelligence community made over the existence of weapons of mass destruction in Iraq and has appeared to back Assange in tweets.

Clapper also said there is a difference “between skepticism and disparagement” of the intelligence community. Trump has taken to Twitter, referring to “Intelligence” and its officials in quotations.

Clapper also testified that there is no evidence the Russian hacking changed vote tallies “or anything of that sort.” He did say, however, there is no way of gauging the impact of Russia’s actions “on choices the electorate made.”

McCain asked Clapper if the Russian cyber intrusion constituted “an act of war.” Clapper responded that constitutes “a very heavy policy call,” which, he said, “I don’t think the intelligence communities should make.”

But he did say what was done carried heavy “gravity.”

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