A 22-month investigation into Donald Trump's alleged links to Russia has found no one involved with his presidential campaign "conspired or coordinated with Russia" to win the 2016 election, according to the US Attorney General.
But it does not exonerate the President, the summary report says.
The report, compiled by Special Counsel Robert Mueller, said there were two main efforts to influence the 2016 election - firstly through the Internet Research Agency [IRA] troll farm to "conduct disinformation and social media operations in the United States designed to sow discord, eventually with the aim of interfering with the election".
No Trump associate "knowingly conspired or knowingly coordinated with the IRA in its efforts", the Attorney General's letter says, summarising Mueller's report.
The second was the Russian government's hacking efforts.
"The Special Counsel found that Russian government actors successfully hacked into computers and obtained emails from person affiliated with the [Hillary] Clinton campaign and Democratic Party organisations, and publicly disseminated those materials through various intermediaries, including WikiLeaks".
Though several people were charged in relation to those efforts, "the Special Counsel did not find that the Trump campaign, or anyone associated with it, conspired or coordinated with the Russian government in these efforts, despite multiple offers from Russian affiliated individuals to assist the Trump campaign".
During the investigation, 34 individuals and groups were indicted and convicted. No further indictments are expected from Mueller's team.
On obstruction of justice, the Special Counsel did not draw any conclusions.
"The Special Counsel states that 'while this report does not conclude that the President committed a crime, it also does not exonerate him'."
Mueller said in his report it's up to the Attorney General to decide whether to charge Trump with obstruction of justice for firing FBI director James Comey in early 2017.
Barr said the "evidence… is not sufficient to establish that the President committed an obstruction of justice offence".
Mueller said it couldn't be determined beyond a reasonable doubt that Trump acted "with corrupt intent", partly because many of Trump's actions "took place in public view".
Mueller's investigation involved 40 FBI agents, 2800 subpeonas, nearly 500 search warrants and requests to 13 foreign governments for information. Several former Trump campaign aides and associates were convicted and jailed as a result.
Trump has always flatly denied there was any collusion.
He took to Twitter soon after the letter's release to claim "complete and total exoneration", despite the report saying that was not the case.
"Not a 'summary' from his handpicked Attorney General. AG Barr, make the full report public. Immediately."
"Good day for the rule of law. Great day for President Trump and his team. No collusion and no obstruction," tweeted Republican Senator Lindsey Graham.
The New York Times reported Trump told friends at his resort in Florida he had been the victim of an attempted coup.
White House spokesperson Sarah Sanders said it was a "total and complete exoneration", despite the report saying it wasn't.
The US Department of Justice has a policy of not charging sitting US Presidents with crimes.