A recent attempt to rescue American journalist James Foley and others in Syria failed, a U.S. official told CNN on Wednesday.
The revelation came as new details emerged about the journalist's final days in the hands of ISIS terrorists.
The U.S. Department of Defense confirmed a rescue attempt was carried out this summer in Syria, but did not say whether Foley was among those U.S. officials had hoped to free.
"Unfortunately, the mission was not successful because the hostages were not present at the targeted location," Pentagon spokesman Rear Adm. John Kirby said, according to CNN.
But the U.S. official, speaking on condition of anonymity, said the mission was to free Foley and other American hostages.
The news broke a day after the Islamic State (IS, formerly ISIS) released a grisly video that showed Foley being beheaded and warned that a second American journalist would be killed if the United States did not end its military operations in Iraq.
Hours earlier on Wednesday, it was revealed that Foley's family was told a week ago in an e-mail sent by his captors that the journalist would be executed.
"The message was vitriolic and filled with rage against the United States. It was deadly serious," said Philip Balboni, CEO of the online publication GlobalPost, which employed Foley.
"Obviously, we hoped and prayed that would not be the case ... Sadly, they showed no mercy," he added, according to CNN.
In the video Foley is seen on his knees as a man cloaked in black -- his face covered -- stands behind him.
Foley is then executed.
The video of his killing also shows another U.S. journalist, believed to be Steven Sotloff. The militant in the video, who speaks English with what sounds like a British accent, says the other American's life hangs in the balance, depending on what President Barack Obama does next in Iraq.
Obama on Wednesday released a statement about Foley in which he slammed the IS group.
"They abduct women and children, and subject them to torture and rape and slavery. They have murdered Muslims - both Sunni and Shia - by the thousands," said Obama. "They target Christians and religious minorities, driving them from their homes, murdering them when they can for no other reason than they practice a different religion. They declared their ambition to commit genocide against an ancient people."
"ISIS speaks for no religion," Obama insisted. "Their victims are overwhelmingly Muslim, and no faith teaches people to massacre innocents. No just God would stand for what they did yesterday, and for what they do every single day."
"ISIS has no ideology of any value to human beings," he continued. "Their ideology is bankrupt. They may claim out of expediency that they are at war with the United States or the West, but the fact is they terrorize their neighbors and offer them nothing but an endless slavery to their empty vision, and the collapse of any definition of civilized behavior."