US aircraft have launched a fresh wave of bombing raids against Islamic State militants in Syria, in the fifth consecutive day of air strikes in the country, a defense official told AFP on Friday.
"I can confirm US air operations are ongoing in Syria," said the senior official, who spoke on condition of anonymity.
The mission is now similar to US-led air raids undertaken in Iraq, with "near continuous" combat flight operations over Syria, the official said.
The US military's Central Command, which leads American forces in the Middle East, did not issue any details of the latest air strikes.
Pentagon chief Chuck Hagel told reporters earlier Friday that US and Arab coalition warplanes have carried out more than 40 bombing strikes this week against the IS group, including attacks on the organization's oil refineries.
"Combined with our ongoing efforts in Iraq, these strikes will continue to deny ISIL (IS group) freedom of movement and challenge its ability to plan, direct, and sustain its operations," Hagel said.