Donald Trump has called for Russia to stop fomenting unrest around the world, but pointedly stopped short of condemning Moscow for meddling in the US election.
On the eve of his first meeting with Russian President Vladimir Putin, Mr Trump delivered a speech in Warsaw, Poland, and vowed to confront "new forms of aggression" targeting the West.
Buoyed by an electrified crowd in Poland chanting his name, Mr Trump sought to show he was not overlooking Russian actions that have caused global consternation, especially from nearby nations in eastern and central Europe.
He warned that Western interests were being tested by "propaganda, financial crimes and cyber warfare", forcing Nato to adapt.
"We urge Russia to cease its destabilising activities in Ukraine and elsewhere, and its support for hostile regimes including Syria and Iran, and to join the community of responsible nations in our fight against common enemies and in defence of civilisation itself," he said in a speech in Warsaw's Krasinski Square.
It was a critique the president did not appear to extend to Russia's actions last year during the presidential campaign.
In a news conference before his speech, Mr Trump questioned the veracity of American intelligence about foreign meddling in the US election, arguing that Russia was not the only country that may have interfered.
"Nobody really knows for sure," the president said.
As US investigations into Russia's meddling forge ahead, he is under intense scrutiny for how he handles his first face-to-face session with Mr Putin.
US intelligence officials say the unpredictable Russia leader ordered interference into the 2016 election that took Mr Trump to the White House.
The pair plan to sit down on Friday in Hamburg, Germany, on the sidelines of the G20 summit.
Loath to cast a shadow on his election victory, Mr Trump has avoided firmly blaming Moscow for campaign hacking in the past, and on Thursday, he was similarly elusive.
He argued variously that it could have been Russia, probably was Russia and indeed was Russia, while insisting it could have been other countries too, adding: "I won't be specific."
The president sought to redirect scrutiny towards his predecessor, Barack Obama, accusing him of allowing Moscow to meddle on his watch.
Though the Obama administration warned Russia publicly and privately before Election Day to stop interfering, questions have since been raised about whether he acted firmly enough to stop the threat.
"They say he choked. Well, I don't think he choked," Mr Trump said. "I think he thought Hillary Clinton was going to win the election, and he said, 'Let's not do anything about it'."
Using information collected by the FBI, CIA and National Security Agency, the US national intelligence director last year concluded that Moscow was behind the hack of Democratic Party email systems and attempted to influence the 2016 election to benefit Mr Trump.
The Obama administration said the effort was directed from the "highest levels" of Russia's government - a reference to Mr Putin.