June 18, 2013. Donald Trump tweeted: "The Miss Universe Pageant will be broadcast live from MOSCOW, RUSSIA on November 9. A big deal that will bring our countries together!" He later added: "Do you think Putin will be going - if so, will he become my new best friend?" October 17, 2013 Trump tells chat show host David Letterman he has conducted "a lot of business with the Russians."

An FBI agent tells a tech-support contractor at the Democratic National Committee it may have been hacked. On May 18, 2016, James Clapper, the director of National Intelligence, says there were "some indications" of cyberattacks aimed at the presidential campaigns. On June 14, 2016 the DNC announces it had been the victim of an attack by Russian hackers.

Senator Jeff Sessions — an early Trump endorser who led his national security advisory committee — meets Russian Ambassador Sergey Kislyak and a group of other ambassadors at a Republican National Convention event.

Julian Assange's WikiLeaks publishes 20,000 emails stolen from the DNC, appearing to show a preference for Hillary Clinton over Senator Bernie Sanders.

The FBI announces it is investigating the DNC hack saying "a compromise of this nature is something we take very seriously."

Donald Trump is elected president of the United States. On November 9, the Russian parliament burst into applause at the news.

Russian Deputy Foreign Minister Sergey Rybakov says there "were contacts" between the Russian government and the Trump campaign during the election campaign. The Trump campaign issues a firm denial.

Trump names General Michael Flynn as his national security adviser. The former Defense Intelligence Agency chief was a top foreign policy adviser in Trump's campaign. Flynn resigned in February after failing to disclose full details of his communication with Russian Ambassador Sergey Kislyak.

Acting Attorney General Sally Yates tells White House counsel Don McGahn that Flynn made false statements regarding his calls with Kislyak. On January 30, Trump fires Yates for refusing to enforce his travel ban, which was later blocked by federal courts.

Trump says he has "total confidence" in Attorney General Jeff Sessions. Sessions announces he will recuse himself from any investigation into ties between Russia and the Trump campaign.

FBI Director James Comey confirms before the House Select Committee on Intelligence that the FBI was investigating possible links between Russia and the Trump campaign.

In a letter announcing the termination, Trump writes: "While I greatly appreciate you informing me, on three separate occasions, that I am not under investigation, I nevertheless concur with the judgment of the Department of Justice that you are not able to effectively lead the Bureau."

Deputy Attorney General Rod Rosenstein appoints former FBI Director Robert Mueller to look into Russia's interference in the 2016 election and possible collusion with the Trump campaign.

Shortly after Mueller convenes a grand jury for the investigation, the FBI seizes documents from one of Paul Manafort's properties as part of a raid for Mueller's probe. The former Trump campaigner manager stepped down in August 2016 after allegations surfaced that he had received large payments linked to Ukraine's former pro-Russian government.

Donald Trump Jr. tells the Senate Judiciary Committee he has not colluded with a foreign government. The closed-door interview relates to his June 2016 meeting with Russian lawyer Natalia Veselnitskaya, which was also attended by his brother-in-law, Jared Kushner, and then-campaign manager Paul Manafort. Trump Jr.’s emails, however, suggest the meeting was supposed to produce dirt on Clinton.

Facebook, Twitter and Google reportedly tell US media they have evidence that Russian operatives exploited platforms to spread disinformation during the 2016 US presidential election. The three companies are appear before the Senate Intelligence Committee in November 2017.

Trump and Russian President Vladimir Putin meet in Helsinki for their first-ever summit. During the trip, Trump publically contradicts the findings of US intelligence agencies who concluded that Russia interfered in the 2016 presidential election.

Attorney General Jeff Sessions resigns from his post, under reported pressure from Trump. The president then appoints a critic of the Mueller probe as his successor, but later nominates William Barr to be the next attorney general in December 2018.

Trump's former long-time personal lawyer, Michael Cohen, pleads guilty to lying to Congress about discussions in 2016 on plans to build a Trump Tower in Moscow. The FBI raided his home earlier that year in April. He would later be sentenced to three years in prison. In 2019, he tells Congress that Trump is a "racist" and a "con man."

Roger Stone, a longtime Trump associate and Republican operative, is arrested at his home in Florida for lying to Congress about having advance knowledge of plans by WikiLeaks to release emails from the Democratic Party that US officials say were stolen by Russia.

Manafort is found guilty of conspiracy charges and handed an additional sentence, bringing his total prison sentence to 7.5 years. In August 2018, a court in Virginia found him guilty of eight charges, including tax and bank fraud. He also pleaded guilty to two conspiracy counts.

Special counsel Robert Mueller submits a confidential 448-page report on the findings of his investigation to the US Justice Department. The main conclusions of the report are made public when they are given to Congress. A redacted version of the report is released to the public on April 18, though Democrats call for the full report to be released.

The final report concluded that no one involved in Trump's 2016 election campaign colluded with Russia. Attorney General William Barr said the report provided no evidence that Trump obstructed justice, but stopped short of fully exonerating the president. Reacting to the findings, Trump described the probe as an "illegal take-down that failed," and said there was "complete and total exoneration."

In late March, Mueller writes a letter expressing concerns over the way Barr portrayed his report. The attorney general says the special counsel's letter was "a bit snitty" while testifying in front of the Senate Judiciary Committee in May. Barr then cancels a subsequent appearance before the House Judicial Committee, citing "unprecedented and unnecessary" hearing conditions.

Robert Mueller's congressional testimony on the Russia probe was again inconclusive. He sometimes struggled with his answers or avoided queries. To the Democrats frustration he appeared to do little to give any encouragement to the notion that President Trump could be impeached, though he did suggest he might be prosecuted for obstruction of justice crimes after he leaves the White House.