The US Secretary of State Rex Tillerson and his Russian counterpart Sergei Lavrov are to hold talks in Moscow today.
Their meeting comes on the same day the UN Security Council is due to vote on a draft resolution demanding that the Syrian government cooperate with an investigation into the suspected chemical attack last week in Idlib province.
Russia is reported to have threatened to use its veto to block the measure.
Diplomats have said the outcome of the resolution will be decided during the talks in Moscow.
Britain, France and the United States put forward the revised resolution following the suspected sarin gas attack in the rebel-held town of Khan Sheikhun that left dozens dead.
The Organisation for the Prohibition of Chemical Weapons has dispatched a fact-finding mission to Syria.
The UN Organisation for the Prohibition of Chemical Weapons Joint Investigative Mechanism is also investigating alleged chemical weapons use to determine who is responsible.
The US Defence Secretary has said the United States has ‘no doubt’ the regime of Syrian President Bashar al-Assad was responsible for last week’s suspected toxic gas attack.
In his first press conference since becoming Defence Secretary, James Mattis added that US military policy on Syria has not changed and remains focused on defeating the so-called Islamic State group.
He said the US cruise missile strikes on a Syrian airbase were in response to a separate issue – the breach of an international prohibition against the use of chemical weapons.