Special counsel Robert Mueller has submitted his report on the two-year investigation of Russian meddling in Donald Trump's 2016 election. A Justice Department official said Mueller's report does not recommend any further indictments. Attorney General William Barr will summarise the report and provide the "principal conclusions" to Congress, possibly as soon as this weekend. Trump has denied collusion and obstruction, repeatedly condemning the probe as a "witch hunt". But earlier he said he doesn't mind if the public is allowed to see the report. CGTN's Owen Fairclough charts the course of the controversy which began before Trump was elected.

OWEN FAIRCLOUGH FBI HEADQUARTERS, WASHINGTON DC "Donald Trump's presidency has been overshadowed by two crucial questions: Did he and his campaign team collude with Russia to swing the 2016 election in his favor and did Trump try to obstruct justice. At the FBI headquarters, special counsel Robert Mueller was in charge of finding out."

His inquiry goes all the way back to what happened in another famous building-Trump Tower in June 2016.

A Kremlin-linked Russian lawyer had offered Trump's campaign team potentially damaging material on rival candidate Hillary Clinton to help Trump beat her.

The following month, July 2016, the FBI launches a counter-intelligence operation looking at possible collusion. The bureau already knows Russian hackers are trying to interfere with the election.

OWEN FAIRCLOUGH FBI HEADQUARTERS, WASHINGTON DC "Trump wins the presidency in November. But from the outset, his White House is besieged by questions over his links to Russia."

National Security Adviser Michael Flynn resigns for misleading the Administration over talks with the then Russian ambassador to the U.S.

Then Attorney General Jeff Sessions recuses himself from investigations into collusion because he failed to disclose that he'd met twice with the same Russian Ambassador.

In May, Trump fires FBI Director James Comey, having repeatedly asked him to drop an inquiry into Flynn's Russia contacts.

Robert Mueller is appointed special counsel with Trump has repeatedly called Mueller's inquiry a "witch hunt".

"There was no collusion at all."

Even while next to Russian President Vladimir Putin.

OWEN FAIRCLOUGH FBI HEADQUARTERS, WASHINGTON DC "And after a barrage of criticism from Trump for not protecting him from Mueller, Attorney General Jeff Sessions resigned at Trump's request-raising questions about the future of this FBI inquiry."

Session's permanent replacement, William Barr, says he'll make as much of Mueller report available to the public as possible.

Owen Fairclough, CGTN, Washington.