US President Donald Trump has flown back to the US and into a furious storm of controversy, after suggesting he trusts Vladimir Putin over his own intelligence services.
US investigators believe Russian hackers and propaganda experts interfered in the 2016 election, in which Mr Trump beat Democrat Hillary Clinton.
But in a joint news conference with the Russian leader, Mr Trump told reporters: "I have great confidence in my intelligence people but I will tell you that President Putin was extremely strong and powerful in his denial today."
His comments have been strongly criticised by a long list of senior American political figures, including many from his own party who have expressed their disgust.
Some have called his comments "thoughtless", others have condemned them as "shameful" - and one has gone as far as calling them "nothing short of treasonous".
Following his face-to-face talks with Mr Putin, the US president criticised the probe into alleged meddling as "a disaster for our country", adding: "There was no collusion at all - everybody knows it."
Mr Putin insisted: "The Russian state has never interfered and is not planning to interfere in the USA's internal affairs, including the election process."
But he admitted he had wanted to see Mr Trump win the election, because "he talked about bringing the US-Russia relationship back to normal".
Mr Trump even blamed his own country's "foolishness and stupidity" for the state of the relationship between the two countries.
After the conference, he tweeted:
As I said today and many times before, “I have GREAT confidence in MY intelligence people.” However, I also recognize that in order to build a brighter future, we cannot exclusively focus on the past – as the world’s two largest nuclear powers, we must get along! #HELSINKI2018
— Donald J. Trump (@realDonaldTrump) July 16, 2018
Mr Trump's behaviour was also met with anger back in the US, with John Brennan, CIA director between 2013 and 2017, leading the charge.
He wrote on Twitter: "Donald Trump's press conference performance in Helsinki rises to and exceeds the threshold of high crimes and misdemeanours.
"It was nothing short of treasonous.
"Not only were Trump's comments imbecilic, he is wholly in the pocket of Putin."
Donald Trump’s press conference performance in Helsinki rises to & exceeds the threshold of “high crimes & misdemeanors.” It was nothing short of treasonous. Not only were Trump’s comments imbecilic, he is wholly in the pocket of Putin. Republican Patriots: Where are you???
— John O. Brennan (@JohnBrennan) July 16, 2018
Even some Republican politicians were critical.
Republican senator Jeff Flake said: "I never thought I would see the day when our American president would stand on the stage with the Russian president and place blame on the United States for Russian aggression."
Fellow Republican senator John McCain described the Helsinki summit as a "tragic mistake", adding: "Today's press conference in Helsinki was one of the most disgraceful performances by an American president in memory.
"The damage inflicted by President Trump's naivety, egotism, false equivalence, and sympathy for autocrats is difficult to calculate."
Today’s press conference in #Helsinki was one of the most disgraceful performances by an American president in memory.
My full statement on the #HelsinkiSummit: https://t.co/lApjctZyZl
— John McCain (@SenJohnMcCain) July 16, 2018
House speaker and Republican Paul Ryan, who has been reluctant to criticise Mr Trump in recent months, said there was "no question" that Russia had interfered in the presidential election.
He said Mr Trump "must appreciate that Russia is not our ally", adding: "There is no moral equivalence between the United States and Russia, which remains hostile to our most basic values and ideals."
Director of national intelligence Dan Coats said: "We have been clear in our assessments of Russian meddling in the 2016 election and their ongoing, pervasive efforts to undermine our democracy."
