Watch Live: House Intelligence Hearing With John Brennan

Updated at 11:33 a.m. ET

Former CIA Director John Brennan testifies Tuesday — on Russian meddling in the 2016 presidential election and Russia's use of "active measures" — before the House Intelligence Committee. Brennan is also expected to be questioned about the many leaks regarding national security issues since President Trump took office.

In his opening statement, Brennan recounted how he had briefed congressional leaders in August of last year, including House Speaker Paul Ryan, R-Wisc., Senate Majority Leader Mitch McConnell, R-Ky., and the chairs and ranking members of the House and Senate Intelligence Committees about the "full details" of what he knew of Russia's interference in the 2016 election. Brennan said he became convinced last summer that Russia was trying to interfere in the campaign, saying "they were very aggressive."

Brennan said he is "aware of information and intelligence that revealed contacts and interactions between Russian officials and U.S. persons involved in the Trump campaign." Brennan said that concerned him, "because of known Russian efforts to suborn such individuals," and that it raised questions about whether or not the Russians "were able to gain the cooperation of those individuals." Brennan added he didn't know if "collusion existed" between the Russians and those he identified as involved in the Trump campaign.

Brennan told the committee he believed that Russia anticipated that Democrat Hillary Clinton would be the likely winner of the presidential race, and that they tried to "damage and bloody" her before Election Day. Had she won, Brennan said, Russia would have continued to attempt to "denigrate her and hurt her" during her presidency. If Russia had collected more information about Clinton that they did not use against her during the campaign, Brennan said they were likely "husbanding it for another day."

On another question, Brennan criticized President Trump's reported sharing of classified intelligence with Russia officials. Brennan said if reports were accurate, Trump violated "protocols" by sharing the information with Russia's foreign minister and ambassador to the U.S.

Brennan also said he was "very concerned" by the release of what he said appears to be classified information from the Trump White House. He said there appear to be "very, very damaging leaks, and I find them appalling and they need to be tracked down."

Brennan led the CIA during the Obama administration from 2013-2017. Prior to that, Brennan was a top counterterrorism and homeland security adviser to President Barack Obama.

Tuesday's public hearing represents an effort by the House Intelligence Committee to get its Russia investigation back on track after political squabbling and concerns about information-sharing between its chairman, Rep. Devin Nunes, R-Calif., and White House aides sidelined the committee's work. After pressure from Democrats, Nunes has turned over leading the committee's Russia investigation to Rep. Mike Conaway, R-Texas, who is also a CPA.

Following Brennan's public testimony Tuesday morning, he will testify in a closed-door session. His testimony comes a day after former Trump national security adviser Michael Flynn refused to hand over documents to the Senate Intelligence Committee, which is also investigating Russian interference in the election, in response to a congressional subpoena from that committee. Flynn cited his Fifth Amendment right against self-incrimination.