Probe continues into possible Russian collusion with Trump campaign
The chairman of the US senate intelligence committee has said the panel is continuing to investigate possible collusion between Russia and associates of Donald Trump's election campaign - but has not reached a conclusion yet.
Senator Richard Burr, a North Carolina Republican, gave an update on the committee's investigation into Russian interference in the 2016 presidential election.
He was joined by the committee's top Democrat, senator Mark Warner of Virginia.
Mr Burr said the committee has interviewed more than 100 witnesses as part of its investigation and that more work still needs to be done.
He said: "The issue of collusion is still open."
Mr Warner said there is a "large consensus" that Russians hacked into political files and released that information in an effort to influence the election.
He said the Russian effort to sway the election also involved attempts to test the vulnerabilities of 21 states' election systems.
Mr Burr said no vote counts were altered.
The committee is one of several that are investigating Russian interference in the election and potential collusion between Russia and associates of the Trump campaign.
The politicians said though they have reached no conclusion about whether the Trump campaign colluded with the Kremlin, their investigation has left no doubt about a multi-pronged Russian effort to meddle in American politics.
"The Russian intelligence service is determined, clever and I recommend every campaign and every elected official take this seriously," Mr Burr said.
He said they had reviewed more than 100,000 pages of documents during their nine-month investigation.
But the committee has still yet to interview many witnesses related to the Trump campaign, including Donald Trump Jr.
One witness the politicians say they have been unable to question is Christopher Steele, a former British spy believed to have compiled a dossier of allegations about Mr Trump's connections to Russia.
The committee "has hit a wall" in its requests to interview Mr Steele as he has not accepted any of the offers.
Mr Burr said: "The committee cannot really decide the credibility of the dossier without understanding things like who paid for it, who are your sources and subsources?"
The committee has been examining how fake accounts on Facebook and Twitter were used by Russians to promote propaganda and misinformation during the 2016 election.
Twitter has agreed to appear for a public hearing before the committee on November 1, and Facebook has said it will also participate.
Facebook turned over more than 3,000 Russia-linked ads to Congress this week.
The company has said the ads focused on divisive social and political messages, including LGBT issues, immigration and gun rights and were seen by an estimated 10 million people before and after the election.
Special counsel Robert Mueller is leading a separate criminal investigation into whether the Trump campaign colluded with the Kremlin.