Western and Arab governments have pledged more political and material support to the Syrian opposition, Reuters reports citing a statement released.
The Friends of Syria group deplored the "unabated" arms supply to President Bashar al-Assad's government by third countries.
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Although Israel was widely believed to have been behind the airstrike on September 6, it has never before commented publicly on it.
Top temperatures of 12 Celsius (54 F).
Sarah Sanders, the White House spokeswoman, acknowledged that the attack wasn’t even mentioned in the phone call.