The United States has said it and its allies have begun bombing positions held by Islamic State of Iraq and Levant in Syria, the first such attacks since forming a coalition to confront the group.
The attacks began at about 00.30 GMT on Tuesday, with the first wave of about 20 strikes taking about 90 minutes. Other waves were expected in the coming hours.
The US did not confirm what was targeted, but reports on social media stated that areas of Raqqa - the ISIL stronghold in Syria - were hit.
Tens of ISIL fighters were killed or wounded in the strikes on Raqqa and surrounding areas, according to the Syrian Observatory for Human Rights, which gathers information from a network of activists on the ground.
"More than 20 members of ISIL were killed in strikes on two of the organization's positions in Raqqa province. The strikes completely destroyed the two positions as well as vehicles stationed there," the monitoring group said.
Damascus 'notified'
Syria's foreign ministry said Damascus had been informed by Washington about the imminent airstrikes.
Jordan's minister of information and communication, Mohamamd Al Momani, confirmed his country participated in the strikes. Momani said the airstrikes would continue in the coming period and that four countries were involved in the operation, including Jordan.
The attacks come just two weeks after the US formed a coalition to confront the ISIL group, which has taken over large areas of Syria and Iraq and declared a "caliphate".
Syrian Kurds urged US airstrikes against ISIL
The coalition includes Nato, non-members including Australia and Arab nations.
The US president, Barack Obama, said on September 10 that an expanded campaign would degrade and ultimately destroy the group.
The attacks also come a day after ISIL's spokesman, Abu Mohammed al-Adnani, called on supporters of the group to attack foreigners wherever they are.
PHOTO CAPTION
An F/A-18C Hornet coming from Iraq lands on the flight deck of a US navy aircraft carrier in the Gulf on August 15, 2014
Al-Jazeera