President Donald Trump opened his first meeting with Russian president Vladimir Putin on Friday by raising US concerns about Moscow's meddling in the 2016 presidential election, US secretary of state Rex Tillerson said.
Mr Tillerson said Mr Putin denied being involved and went on to say there was "clear positive chemistry" between the leaders during a meeting that lasted more than two hours although initially 35 minutes had been set aside.
Mr Trump's decision to confront Mr Putin directly over election interference fulfilled ardent demands by US politicians of both parties that the president not shy away from the issue in his highly anticipated meeting with Mr Putin.
Mr Trump has avoided stating unequivocally in the past that Russia interfered, even as investigations proceed into whether Mr Trump's campaign colluded with Russians who sought to help him win.
"I think the president is rightly focused on how do we move forward from something that may be an intractable disagreement at this point," Mr Tillerson said.
Both Mr Trump and Mr Putin appeared determined not to let the issue obstruct future cooperation, though their aides offered differing descriptions of where they left the matter at the conclusion of their meeting, which spanned more than two hours.
Russian foreign minister Sergey Lavrov, who attended the meeting along with Mr Tillerson, said Mr Trump accepted Mr Putin's assurances that Russia did not meddle in the US election.
But Mr Tillerson said the Russians had asked for "proof and evidence" of its involvement.
A day earlier, Mr Trump had said Russia probably meddled but that other countries likely did, too.
On one point, Mr Putin and Mr Trump agreed, Mr Tillerson said: the issue has become a hindrance to better relations between the two powers.
Speaking to reporters after the meeting, Mr Tillerson said the discussion about the election meddling was "robust and lengthy".
Mr Tillerson said the two leaders had agreed to continue the discussion, with an eye toward securing a commitment that Russia will not interfere in US affairs in the future.
In their meeting, the two also discussed a ceasefire deal for southwestern Syria that was reached by Russia and the United States and first reported on Friday by The Associated Press.
Though the US and Russia have held conflicting views on Syria in the past, Mr Tillerson said Russia had an interest in seeing the Mideast nation become a stable place.
Though Mr Tillerson said details about the ceasefire need to be worked out, Mr Lavrov said that Russian military police will monitor the ceasefire, with a monitoring centre set up in Jordan, another party to the deal.
Both the Russians and the Americans took pains to describe the meeting as "constructive," cordial and wide-ranging, covering key topics including cyber security and North Korea.
Still, Mr Tillerson said no next meeting for Mr Putin and Mr Trump had been scheduled.
"The two leaders connected very quickly. There was a very clear positive chemistry," said Mr Tillerson.
The former Exxon Mobil chief executive has done business in Russia and is one of the only senior members of Mr Trump's administration who has prior experience dealing with Mr Putin.
The meeting, originally scheduled for 35 minutes, clocked in at two hours and 16 minutes.
"There was so much to talk about," said Mr Tillerson. "Neither one of them wanted to stop."
He added that at one point, aides sent in first lady Melania Trump to try to wrap up the talks, but the meeting went on another hour after that, "so clearly she failed".
The heavily anticipated meeting has been closely scrutinised for signs of how friendly a rapport Mr Trump and Mr Putin will have.
Mr Trump's predecessor, President Barack Obama, had strained ties to Mr Putin, and Mr Trump has expressed an interest in a better US-Russia relationship.
But deep scepticism about Russia in the US and ongoing investigations into whether Mr Trump's campaign coordinated with Moscow during last year's election have made a US-Russia detente politically risky for Mr Trump.
The Putin meeting came midway through a hectic, four-day European visit for Mr Trump, who addressed thousands of Poles in an outdoor speech in Warsaw, Poland, on Thursday.
He met in Germany with Chancellor Angela Merkel, the summit host, and had dinner with two Asian allies, Japanese prime minister Shinzo Abe and South Korean President Moon Jae-in, to discuss North Korea's aggression.