The Russian and US leaders met on the sidelines of a conference in Vietnam
Vladimir Putin and Donald Trump have said there is "no military solution" to the conflict in Syria.
The Russian and US leaders met on the sidelines of the Asia-Pacific Economic Cooperation (APEC) conference in Danang, Vietnam.
In a statement released by the Kremlin after the meeting, the two men are said to be 'determined to defeat ISIS' in Syria.
The statement notes: "[Mr Trump and Mr Putin] confirmed that the ultimate political solution to the conflict must be forged through the Geneva process [...] They also took note of President Assad’s recent commitment to the Geneva process and constitutional reform and elections
"The two Presidents affirmed that these steps must include full implementation of [UN Security Council Resolution] 2254, including constitutional reform and free and fair elections under UN supervision, held to the highest international standards of transparency, with all Syrians, including members of the diaspora, eligible to participate."
The two leaders also stated that 'de-escalation areas' are a key step towards reducing violence in Syria, and called on all UN member states to increase humanitarian contributions.
In comments quoted by Reuters, Donald Trump later told reporters on Air Force One that the agreement with Putin will "save tremendous numbers of lives".
The US president added: “We spoke intermittently during that roundtable. We seem to have a very good feeling for each other and a good relationship considering we don’t know each other well."
Russia has been a key ally to Syrian leader Bashar al-Assad's regime in the civil war that has devastated Syria since 2011.
The US, meanwhile, has led a coalition targeting Islamic State forces in the country, mainly through the use of airstrikes.
Hundreds of thousands of people have been killed in the ongoing, multi-side conflict in Syria - with some estimates putting the death toll at almost half a million people.
Trump's informal meeting with Putin in Danang came amid the ongoing investigations into alleged Russian interference in last year's US election.