WASHINGTON, August 21. /ITAR-TASS/. The US “attempted a rescue operation recently to free a number of American hostages held in Syria”, the Pentagon said in a statement on Wednesday.

It said the operation “involved air and ground components and was focused on a particular captor network within ISIL (the Islamic State of Iraq and the Levant – former name of the Islamic State group)”.

“Unfortunately, the mission was not successful because the hostages were not present at the targeted location,” the Pentagon said.

Lisa Monaco, assistant to the president for Homeland Security and Counterterrorism, said the rescue attempt of Americans held hostage by the Islamic State occurred earlier this summer.

President Obama "authorized action at this time because it was the national security team's assessment that these hostages were in danger with each passing day in (Islamic State) custody," Monaco said.

It was not clear whether the operation had intended to rescue journalist James Foley among others. The Washington Post quoted Obama administration officials who spoke on the condition of anonymity as saying that Foley was among those intended for rescue.

The Islamic State group released a video on Tuesday, showing a purported beheading of journalist James Foley, who went missing in Syria in November 2012.