A United Nations spokesman on Thursday welcomed a joint pledge by Turkey and Russia to cooperate against Daesh.
"We welcome any signs of greater international unity against Daesh," Farhan Haq said during a daily briefing in response to a question about the recent thawing of Turkey-Russia ties.
Regarding the current situation in Aleppo, where nearly 300,000 residents are stranded and in need of humanitarian assistance, Haq said there have been indications of improvements but the overall conditions are dangerous. "Attacks on hospitals and clinics have continued unabated and that seriously jeopardizes the health and welfare of all citizens," he said. "There are some signs that water has been returned to some people in Aleppo but the situation remains precarious for hundreds of thousands."
After Erdoğan and Putin met for the first time earlier this week since Turkish jets shot down a Russian military aircraft last November, the two countries announced new committees to discuss the Syrian crisis, which were to meet for the first time in Moscow on Thursday.
Ankara and Moscow expressed differences of opinion on the future of the regime of Syria's Bashar Assad but both cite the Daesh terrorist group, which controls large swathes of land in Syria and Iraq, as a common enemy.
Later Thursday, the State Department said it remained in close contact with its Turkish allies to fight Daesh and would welcome it if Russia were really interested in taking the fight to the militants.
Asked of the U.S. position regarding reports allegedly Turkey looked to expand its non-NATO defensive security cooperation, agency spokeswoman Elizabeth Trudeau said interoperability was a fundamental tenet of NATO.
"We believe it's important that NATO countries procure military equipment that's interoperable with NATO systems," she said.
Syria has been torn apart by a five-year conflict that has left hundreds of thousands of victims dead and millions displaced, with Turkey alone sheltering more than 2.7 million Syrians.
Aleppo has been a flash-point city in the fighting between opposition groups and Moscow-backed regime forces, with Russia laying siege to the city and suffocating humanitarian efforts.