US Secretary of State John Kerry said on Wednesday that Russia’s military support for Syrian President Bashar al-Assad could raise the risk of confrontation with coalition forces fighting Islamic State there.

US Secretary of State John Kerry said on Wednesday that Russia's military support for Syrian President Bashar al-Assad could raise the risk of confrontation with coalition forces fighting Islamic State there.

In an interview with Italian newspaper La Stampa, Kerry said he had told Russian Foreign Minister Sergey Lavrov the United States was worried by Moscow's military backing for Assad in Syria's civil war, now in its fifth year.

"These actions could provoke a further escalation of the conflict and lead to the loss of more innocent lives, increasing the flow of refugees and risking a confrontation with the anti-ISIL (in reference to the so-called 'Islamic State of Iraq and the Levant' takfiri group) coalition operating in Syria," Kerry said.

He did not spell out what he meant by the coalition. But the United States and allies have been launching air strikes against alleged positions held by the ISIL militant group in Syria, and in neighboring Iraq.

The Zionist entity has also raised concerns that Russian involvement on Assad's side in the conflict in Syria could accidentally lead to confrontations between Russian and Zionist forces there.

Russia has built up naval infantry forces and heavy equipment including tanks and helicopters at Syria's Latakia airbase, US officials say, raising the possibility of air combat missions in Syrian airspace.