Russia's Foreign Minister Sergei Lavrov and US Secretary of State John Kerry discussed Moscow's proposals for the two countries to conduct joint operations against Syrian militants who do not observe a ceasefire in the country, The Nation reports.
In their telephone conversation held on Sunday, the two politicians also discussed the closure of the Syrian border with Turkey to prevent 'militant infiltration', as well as the situation in Ukraine, the Russian foreign ministry said in a statement.
Meanwhile, thousands of civilians have fled an offensive carried out by the Islamic State group against non-militant rebels in northern Syria into territory controlled by a US-supported Kurdish-led alliance, a monitor said on Sunday.
The offensive against the towns of Marea and Azaz threatens to invade the last swathe of territory in the east of Aleppo province held by non-militant rebels and bring Islamic State to the doorstep of the Kurdish enclave of Afrin.
At least 29 civilians have been killed since the terror group launched the attack on Friday, the Syrian Observatory for Human Rights said.
It came as the IS fighters were under attack by the Kurdish-led alliance in Raqa province further east and by the army and allied militia around Falluja in neighboring Iraq.
"More than 6,000 civilians, most of them women and children, were able to flee areas in the countryside of Aleppo province, especially from Marea town and Sheikh Issa village" to its west, the UK-based monitoring group said.