US AND Russian defence chiefs spoke for the first time in over a year yesterday, breaking their silence to discuss the crisis in Syria as Moscow's increasing military buildup raised the prospect of coordination between the former Cold War foes.
The Pentagon said the call lasted about 50 minutes and included an agreement for further US-Russian talks about ways to keep their respective militaries out of each other's way.
Washington last year cut off high-level military talks with Moscow after Russia's annexation of Crimea and intervention in Ukraine.
But Russia's buildup at Syria's Latakia airbase raises the possibility of simultaneous US and Russian air combat missions in Syrian airspace.
Russia will consider any request from the embattled Syrian regime to send its troops to fight Islamic State of Iraq and the Levant (Isil), the Kremlin said yesterday.
The comments are one of the clearest indications to date that troop deployments may be imminent.
Dmitry Peskov, Vladimir Putin's spokesman, said: "If there is a request then, within the framework of bilateral contact and two-way dialogue, it will, of course, be discussed and considered," said.
Russia has denied the presence of any additional forces, although it admits it is supplying President Assad with significant military and technical support. It has refused to rule out air strikes or troop deployments in Syria, where it has a key naval base.
Syria's foreign minister Walid al-Moualem said on Thursday that Russia had provided new weapons and trained Syrian troops how to use them, and told state television the government would be prepared ask Russian forces to fight alongside its troops if needed.
Mr Putin warned earlier this week that Isil's influence has spread "far beyond" the borders of Iraq and Syria, but that it is as yet "too early" to talk about air strikes against Isil.
In figures sharply revised upwards from previous estimates, a top Russian security service official said yesterday that there were 2,400 Russians currently fighting for Isil. Russia has seen a steady flow of its citizens leaving for Iraq and Syria, principally from the mainly Muslim North Caucasus.