"It should be clear to everyone Russian Federation brazenly interfered in our 2016 presidential election process and that they undertook these activities despite our strong protests and explicit warning that they do not do so", Mr Brennan said.
Trump did so after top FBI officials, including now-fired Director James Comey, reportedly refused a White House request to knock down news stories on possible Trump campaign-Russia links, and after Comey reportedly declined Trump's entreaty to end the investigation into former national security adviser Michael Flynn.
The report is also evidence that the Russians were well aware that Trump is easily influenced by those around him and has no core convictions.
As the New York Times also noted, it hasn't yet been confirmed whether the Russian officials were actually successful in influencing either Paul Manafort or Michael Flynn - two of their targets.
Separately, Carter Page, a former foreign policy adviser to Trump's presidential campaign, told Reuters via text message that he would testify before the House Intelligence Committee but was 'still working out details'.
"We will be following up with subpoenas, and those subpoenas will be created to maximize our chance of getting the information that we need", Schiff said at a breakfast in D.C.
Mr Flynn was forced to step down from his post as national security adviser less than a month into the Trump presidency after it was determined that he had misled Mr Pence when he said that he did not discuss Russian sanctions during the presidential transition period.
In addition to the congressional scrutiny, he is a target of an FBI counter-intelligence investigation, a federal probe in Virginia and a Defence Department inspector general's inquiry into the propriety of foreign payments he accepted.
Brennan noted anew that U.S. intelligence agencies had concluded "Russia's goals were to undermine public faith in the United States democratic process, denigrate Secretary (Hillary) Clinton and harm her electability and potential presidency, and to help President Trump's election chances". Now that Trump has been widely rebuked for firing Comey and for other actions relating to the Russian Federation investigation, if the president crosses a line, he knows what he's doing. A spokesman for the committee declined comment on whether Page would testify.
Flynn has failed to voluntarily provide documents that committee members had requested for their probe. Mark Warner (D-Va.), the committee's vice chairman, said he believes Burr's comments that Flynn has more time to comply with the subpoena were correct. Page said he expects to testify sometime during the week of June 6 and wants at least part of his testimony to be public. It wasn't clear if Mr Manafort or Mr Flynn were directly influenced by Russians, or if Russians attempted to do so.
On Tuesday, Brennan, the former CIA director, testified to the House intelligence panel that he had noticed enough contact between Trump associates and Russian Federation during the 2016 campaign to justify an investigation by the FBI.