Amid calls for President Donald Trump to be impeached and the appointment of former FBI director Robert Mueller to oversee the investigation, here is what we know about the probe into Russian-Trump collusion during the 2016 presidential election
How did the investigation begin
Former president Barack Obama ordered US intelligence agencies to assess whether Russia intervened in the 2016 election after a cyber-attack on the Democratic National Committee in July last year and the publication of thousands of personal emails from Hillary Clinton’s campaign manager.
What did intelligence agencies find?
The CIA and FBI found Russian President Vladimir Putin ordered a campaign to undermine confidence in the US electoral system and affect the outcome with a “clear preference” for Trump to win.
President Putin’s associates hacked information, paid social media “trolls” and backed efforts by Russian government agencies and state-funded media to sway public opinion.
What has Trump said about Russia’s role?
Donald Trump has not taken a clear public position, but said in July last year in relation to Hillary Clinton’s emails: “I will tell you this, Russia: if you’re listening, I hope you’re able to find the 30,000 emails that are missing”.
Mr Trump subsequently dismissed reports from US intelligence officials that Russia attempted to intervene in the election on his behalf.
The first time he said he accepted the findings of the intelligence agencies was at a January conference ahead of his inauguration.
“As far as hacking, I think it was Russia,” he said, but then added: “It could have been others also.”
How many investigations are there?
Committees in the House of Representatives and the Senate, along with the US Department of Justice and FBI are known to be investigating.
What has the fallout been?
Trump’s national security adviser Michael Flynn was fired in February.
The White House said Flynn misled Vice President Mike Pence about his contact with Russia’s ambassador to the US, Sergei Kislyak, before MrTrump took office.
Attorney General Jeff Sessions had to recuse himself from involvement in Russia-related probes at the Justice Department because he did not tell Congress of his contacts with Kislyak in 2016.
FBI director James Comey was sacked by Trump on May 9.
Why was Comey fired?
The White House says Mr Comey was fired because of his handling of the Clinton email investigation.
A memo from Deputy Attorney General Rod Rosenstein to President Trump recommended Mr Comey’s dismissal.
It said Mr Comey erred in July last year by announcing the FBI had been examining Mrs Clinton’s use of a private email server and that the case should be closed without prosecution.
A memo Mr Comey wrote after a February meeting with Trump stated the president had asked him to end the FBI’s investigation of Flynn, the New York Times reported.
Mr Trump called Mr Comey a “showboat” and “grandstander” in May.
Mr Comey told the congressional panel in May the idea that he may have affected the election result made him “mildly nauseous”.
What happens now?
Former FBI director Robert Mueller has been appointed as a special counsel to oversee the Trump-Russia probe.
His appointment comes amid a growing Democratic outcry for someone outside the Justice Department to handle the politically charged investigation.