US jets and drones have attacked fighters loyal to the Islamic State group positioned around the Mosul dam in northern Iraq, after US President Barack Obama vowed to end the "cancer" of the group.
The US said its aircraft carried out six raids on Thursday on positions around the dam, which is now under the control of Iraqi and Peshmerga forces, following fierce battles earlier this week to dislodge Islamic State fighters.
The attacks destroyed or damaged four vehicles and "multiple" homemade bomb emplacements, a spokesman for the US central command said, taking to 90 the number of raids conducted by the US in Iraq since August 8.
The strikes come days after the self-declared jihadist group posted a video on the Internet of the beheading of James Foley, a US journalist captured in Syria in 2012, which it said was revenge for US raids on its territory.
The group, which controls large areas of northern Syria and northern and western Iraq, said it would attack US interests if it was further targeted by the US military, and threatened the life of another American citizen it held hostage.
US raid in Syria
US officials disclosed on Wednesday that special forces troops had been sent in to Syria earlier this summer in an unsuccessful attempt to find and repatriate Foley.
"This operation involved air and ground components and was focused on a particular captor network within ISIL," the US said, referencing the former name of the Islamic State.
"Unfortunately, the mission was not successful because the hostages were not present at the targeted location."
Philip Balboni, chief executive of the Global Post, who the journalist worked for, said Foley's family had received a $135m ransom demand from the Islamic State group fighters a week before he was killed.
Obama on Wednesday vowed that the US would not stop its air strikes against the Islamic State, stating the murder of Foley was proof that the fighters stand for no religion.
He called the group a "cancer" with a bankrupt ideology.
"The US will continue to do what we must do to protect our people," Obama said.
"We will be vigilant and we will be relentless. When people harm Americans, anywhere, we do what's necessary to see that justice is done."
Foley was apparently murdered by a fighter with a British accent. The UK government has promised to identify the killer.
"We have not identified the individual responsible on the video but from what we've seen it looks increasingly likely that it is a British citizen. Now this is deeply shocking," David Cameron, the UK prime minister, said on Wednesday.