U.S. spy agencies have what they call conclusive evidence Russia provided hacked material from the Democratic National Committee to WikiLeaks through a third party, three sources have told Reuters.

U.S. officials had concluded months earlier that Russian intelligence agencies had directed the hacking.

But until now, they had been less certain that they could prove Russia also had controlled the release of information damaging to Democratic presidential candidate Hillary Clinton.

The timing of the additional intelligence is important because President Barack Obama has faced criticism from his own party over why it took his administration months to respond to the cyber attack.

Director of National Intelligence James Clapper, National Security Agency Director Mike Rogers and Undersecretary of Defense for Intelligence Marcel Lettre are all expected to appear before the Senate Armed Services Committee on Thursday  to testify on Russia’s role in the cyber attacks.

President-elect Donald Trump has vacillated between pooh-poohing the allegations and accusing the Democrats of being sore losers.

A U.S. intelligence report on the hacking was scheduled to be presented to Obama today and to Trump on Friday.

Meanwhile, the Wall Street Journal is reporting that Trump is planning to restructure the nation’s top intelligence agencies, because he thinks they have become politicised.

Trump in recent tweets had mocked US intelligence agencies on the Russian hacking allegation, comparing it to the Bush era when they spoke of weapons of mass destruction in Iraq that turned out to be false.

Trump rather believed in the testimony by WikiLeaks founder, Julian Assange, who said the Russians were not the source of the leaked  email of Democrat John Podesta and the Democratic National Committee..

CNN however has found the President elect’s latest position and wholehearted endorsement of WikiLeaks and Julian Assange at variance with his position seven years ago, when he advocated death penalty for the group.

The president-elect made the comment on Fox News in 2010, according to  CNN’s KFILE team.

Trump then called the leaking site “disgraceful” after it revealed documents stolen by Army Private Chelsea Manning, known at the time as Bradley Manning.

“I think it’s disgraceful, I think there should be like death penalty or something,” Trump said.