Fawaz Gerges, Director of the Middle East Center at the London School of Economics, has told ITV Daybreak that "it would take a spark to ignite the conflict in Syria."
He added: "The conflict in Syria has mutated and taken a very dangerous turn. It has major implications for regional stability and international peace and security."
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A defence ministry official reportedly said Russia had intensified its campaign in the last 24 hours, with 64 sorties hitting 55 targets.
Some patchy mist and fog overnight as the temperature's dip.
The actor joined hundreds of mourners at the funeral of the 30-year-old make up artist in the village of Cappawhite, Ireland.