Donald Trump and Vladimir Putin have discussed the alleged Russian hacking of last year's US presidential election during their first meeting.
US Secretary of State Rex Tillerson described the exchanges as "robust".
Russian Foreign Minister Sergei Lavrov said Mr Trump had accepted Mr Putin's assertions that his country was not responsible.
But Mr Tillerson said it was not clear whether the two countries would ever come to an agreement on what happened.
"I think the president is rightly focused on how do we move forward from something that may be an intractable disagreement at this point," he added.
The US and Russian presidents held their first face-to-face talks on the sidelines of the G20 summit in the German city of Hamburg, which is being held amid sometimes violent protests.
Other topics discussed during their meeting - which lasted nearly two-and-a-quarter hours, longer than originally planned - included the war in Syria, terrorism and cybersecurity.
- Donald and Vladimir: How do they compare?
- Russia: The 'cloud' over the White House
- Who are the G20 protesters?
- In pictures: Violence at G20 protests
"The president opened the meeting with President Putin by raising the concerns of the American people regarding Russian interference in the 2016 election," Mr Tillerson, part of the US delegation, told reporters afterwards.
"They had a very robust and lengthy exchange on the subject. The president pressed President Putin on more than one occasion regarding Russian involvement.
"President Putin denied such involvement, as I think he has done in the past."