THERESA May gave Russian leader Vladimir Putin an ice-cold glare at the G20 summit before ordering him to stop meddling in world affairs.
The Prime Minister told Putin she held Russian intelligence agents responsible for the attack on former double agent Sergei Skripal and his daughter Yulia in Salisbury.
She gave the Russian hardman the curtest of welcomes as they shook hands before their frosty meeting in Japan.
Afterwards at a press conference in Osaka, Mrs May warned: "There can only be a normalisation of our bilateral relationship if Russia stops the pattern of irresponsible activity that threatens the UK and its allies, such as the use of a deadly nerve agent on the streets of Salisbury."
'IRRESPONSIBLE AND DESTABILISING'
The departing PM added: "We remain open to a different relationship, but for that to happen the Russian government must choose a different path."
During their talk, Mrs May demanded he cease "the irresponsible and destabilising activity that threatens the UK and its allies".
She blasted Russia's "hostile interventions in other countries, disinformation and cyber attacks", saying they undermined "Russia's standing in the world", Downing Street confirmed.
There can only be a normalisation of our bilateral relationship if Russia stops the pattern of irresponsible activity that threatens the UK and its allies, such as the use of a deadly nerve agent on the streets of Salisbury
Theresa May
Earlier the Russian president dismissed the Salisbury incident as "fuss about spies and counter-spies" that was "not worth serious interstate relations" and said "traitors must be punished".
But the British PM used her meeting at the summit to demand Russia hand over the two Russian security agents.
The two men, known under the aliases Alexander Petrov and Ruslan Boshirov, were tracked down by British intelligence and police officers and charged with attempted murder over the incident.
Following the Salisbury attack more than 150 Russian diplomats were expelled from more than 20 countries.
SHOWDOWN
Downing Street said she used their first major showdown since the nerve agent incident to raise the prospect of convicting the duo in the UK.
Mrs May described the assassination attempt as a "truly despicable act that led to the death of a British citizen, Dawn Sturgess".
A statement from Number 10 said: "She was clear that the UK has irrefutable evidence that Russia was behind the attack - based on painstaking investigations and co-operation with our allies.
"She said that this behaviour could never be repeated and that the UK wants to see the two individuals responsible brought to justice.
It's not business as usual and it can't be business as usual with Russia until they stop the sort of acts we have seen them doing around the world
Theresa May
"The Prime Minister underlined that we remain open to different relationship, but for that to happen the Russian government must choose a different path.
"The Prime Minister said the UK would continue to unequivocally defend liberal democracy and protect the human rights and equality of all groups, including LGBT people."
Ahead of the interview, the PM defended her decision to meet Mr Putin in a series of interviews in Japan.
"It's not business as usual and it can't be business as usual with Russia until they stop the sort of acts we have seen them doing around the world," she told ITV News.
The outgoing Prime Minister used her platform on the global stage with Vladimir Putin to give the country a chance to come in from the cold.
The Prime Minister urged Russia to choose a "different path" as she joined world leaders for her last G20 summit.
She called on Russia to change its behaviour as she joined leaders including Donald Trump and Angela Merkel in Osaka, Japan, for the summit.
Mrs May: "Russia can go down a different path if it desists from this sort of activity."
But the Russian president dismissed the Skripal scandal as a fuss that's "not worth five pounds".
Putin also blasted "liberal values" as"obsolete" in an interview ahead of the summit.
He said voters worldwide have rejected lax immigration laws - and that "traditional values" are more important than embracing LGBT rights.
His comments came in a wide-ranging interview with the in which he ripped into western values.
LITVINENKO LASHES OUT AT MAY
Marina Litvinenko, the widow of poisoned Russian defector Alexander Litvinenko, criticised May for agreeing to meet Putin at the summit.
She said the PM failed to mentioned Andrei Lugovoi and Dmitry Kovtun - the two Russian assassins accused of killing her husband in 2006 with a radioactive cup of tea.
Mrs Litvinenko told the : "Mrs May has said nothing about what happened to my husband. He was a British citizen when he died.
"The two suspects for his murder should be brought to justice."
She added:"Putin said we should forget what happened in Salisbury to the Skripals, that they weren’t worth five kopecks. He didn’t mention my husband.
“Lugovoi is now a deputy in Russia’s Duma. How the new prime minister handles relations with Moscow will be crucial.
"He may be tempted to start a new relationship without questions. I hope not."
TRUMP TRADING
The leaders traded brief remarks on Friday about issues they planned to discuss when a reporter shouted to Trump about warning Putin "not to meddle" in the 2020 election.
The president answered "Of course" before he turned to Putin and said, "Don't meddle in the election." He playfully repeated request while pointing at Putin, with the Russian leader smiling as it was translated for him.
President Trump first met with host Japanese Prime Minister Shinzo Abe as the summit kicked off on Friday - just days after he blasted the US-Japan security pact as unbalanced.
MAY'S SWANSONG
Theresa May revealed she was looking forward to returning to the backbenches after leaving No10 next month.
She said it had been a "huge privilege" to be Prime Minister but she was hoping to be able to devote more time to her work as MP for Maidenhead.
But until she leaves, she told Sky News her "mood is one of determination to carry on doing the job that I'm doing and to ensure that I get some very strong messages across to those I'm meeting".
She refused to comment on the battle between Boris Johnson and Jeremy Hunt in their battle to the top job - but said they would need to secure a Brexit agreement and "orderly departure" from the EU.
The new Tory leader will be announced on July 23 and will take over as Prime Minister the following day.
MOST READ IN NEWS
And Angela Merkel was among the throng of world leaders to head to Japan for the summit, just after she sparked fears after she was seen shaking uncontrollably.
She gripped her trembling arms and pursed her lips at a ceremony in Berlin - nine days after footage of her shaking for a whole minute sparked health fears.
Aides blamed dehydration for her last bout of shakes and dismissed health worries - but the fresh video today is likely to renew speculation over her future as leader.
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