The United States and partner nations have carried out air strikes against Islamic State targets in Syria overnight.
The Syrian Observatory for Human Rights reported that scores of fighters had been killed or wounded in the city of Raqqa and surrounding areas
A US official said that Arab countries were involved in the strikes – including Saudi Arabia, the United Arab Emirates, Jordan and Bahrain.
The attacks come just two weeks after the US formed a coalition including 40 countries to fight against Islamic State.
Syria has previously warned that any strikes on Syrian soil without the government’s consent would be considered an act of aggression.
President Bashar-al-Assad had offered to co-operate in coordinating strikes on Islamic jihadists but the US refused.
Russia has said the US should respect Syria’s sovereignty and warned airstrikes may also target government forces loyal to President Assad.