A timeline of key events in the relationship between President Donald Trump and Russian President Vladimir Putin, as well as allegations about Russian interference in the 2016 United States presidential election, in advance of their meeting on Friday:
June 18, 2013
Donald Trump, celebrity businessman and reality TV star, tweets "Do you think Putin will be going to The Miss Universe Pageant in November in Moscow - if so, will he become my new best friend?"
July 1, 2015
American intelligence agencies believe that Russian intelligence penetrated the Democratic National Committee networks this month and continued to have access until at least June 2016.
July 27, 2016
Trump, who repeatedly blasted his opponent Hillary Clinton for use of a private email server, invites Russia to hack into her emails. In the final full press conference of his campaign, Trump declares "Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing,"
Oct. 7, 2016
The Department of Homeland Security and the director of national intelligence release a statement saying they are confident Russia is behind the email hacks. That same day, just hours after Trump's "Access Hollywood" tape is released in which he brags about women letting him grab them, WikiLeaks publishes its first batch of emails belonging to Clinton's campaign chairman John Podesta.
Dec. 30, 2016
President-elect Trump praises Putin — "I always knew he was very smart!" — for not retaliating against sanctions imposed by President Barack Obama for Russia's interference in the election.
Jan. 11, 2017
In a news conference, Trump denies that he has any contacts with Russia and denies salacious allegations made against him in a dossier compiled by a former British intelligence officer.
Jan. 25, 2017
Five days after Trump's inauguration, congressional investigations are opened into Russia's meddling in the election. Several Trump campaign and administration officials have testified or are expected to do so.
Feb. 13, 2017
National Security Adviser Michael Flynn resigns after misleading administration officials, including Vice President Mike Pence, over contacts with Russian officials.
March 20, 2017
FBI Director James Comey confirms in Senate testimony that there is a counterintelligence investigation into ties between the Trump campaign and Russian officials.
May 9, 2017
Trump fires Comey. The next day, during an Oval Office meeting with Russian officials, he calls Comey "a nut job" and says his dismissal relieved "great pressure" due to the Russian investigation, according to The New York Times.
June 2, 2017
Putin ridicules the allegations of Russian meddling in U.S. elections, accusing the Democrats of trying to shift blame for their defeat and likening the accusations against Russia to anti-Semitism.
June 23, 2017
Trump, in a tweet, casts doubt on the assessment made by U.S. intelligence agencies that Russia was behind the election hack. He has done this repeatedly since the election.
July 6, 2017
In Poland a day ahead of his first meeting with Putin since taking office, Trump criticizes Russia's aggression in Ukraine and its support for regimes in Iran and Syria. But he stops short of condemning Russia for election meddling — again casting doubt on the claim — and refuses to say whether he will bring it up with Putin.