World Bulletin/News Desk

The online news publication that employed slain U.S. journalist James Foley has published the full text of the email to his family from his captors in which they said they would execute him in retaliation for U.S. airstrikes.

Boston-based GlobalPost said on Thursday the Foley family had agreed to release the email that it received from ISIL a week before the video of his execution was released on Tuesday.

The publication said it chose "to publish it in full in the interest of transparency and to fully tell Jim's story. We believe the text offers insight into the motivations and tactics of the ISIL."

Foley was beheaded by the group in an act shown in a video released in which ISIL called for the United States to end its airstrikes in Iraq.

The email addressed as "a message to the American government and their sheep like citizens," said: "You were given many chances to negotiate the release of your people via cash transactions as other governments have accepted."

The group added that it also offered prisoner exchanges for "Muslims currently in your detention."

Instead, the note added, "now you return to bomb the Muslims of Iraq once again, this time resorting to Arial attacks and "proxy armies", all the while cowardly shying away from a face-to-face confrontation!"

Asserting that the United States did not spare women, children or the elderly, the group added: "We will NOT spare yours!"

The email ended with a declaration that Foley "will be executed as a DIRECT result of your transgressions towards us!"

Highlighting what it called inaccuracies in the email, GlobalPost said the Foley family "was not 'given many chances to negotiate' for Jim's release."

"After more than a year without contact, the Foleys received their first message from Jim's captors on Nov. 26, 2013, asking for money, fast," the publication added.

"After the militants had proved to the Foleys and investigators that they were in fact holding Jim, they made their sole demand for a ransom of 100 million euros (about $132 million) or the release of unspecified prisoners held by the United States," it said.

The Foleys did not hear back until the threatening email this month, GlobalPost said.

The family passed the message on to the U.S. government, GlobalPost's chief executive, Phil Balboni, said in an interview earlier on Thursday, adding that the FBI helped craft a response, pleading for mercy.

Pentagon: Threat 'beyond anything we've seen'

Meanwhile, U.S. military leaders said the sophistication, wealth and military might of ISIL militants represent a major threat to the United States that may surpass that once posed by al Qaeda.

"They are an imminent threat to every interest we have, whether it's in Iraq or anywhere else," Defense Secretary Chuck Hagel told reporters at the Pentagon.

Hagel's assessment of ISIL, which gained strength during Syria's civil war and swept into northern Iraq earlier this summer, sounded a note of alarm.

Asked if the organization posed a threat to the United States comparable to that of the attacks of Sept. 11, 2001, Hagel said it was "as sophisticated and well-funded as any group we have seen."

"They are beyond just a terrorist group. They marry ideology, a sophistication of ... military prowess. They are tremendously well-funded. This is beyond anything we've seen."

Hagel spoke as the United States continued attacking ISIL targets in Iraq. In the past two weeks, U.S. drones and fighter jets have conducted 89 airstrikes against militant targets in northern Iraq.

So far, President Barack Obama has sought to limit his renewed military campaign in Iraq to protecting American diplomats and civilians under direct threat. Obama ended the war in Iraq that killed thousands of American soldiers and consumed U.S. foreign policy for nearly a decade,

Even after the gruesome killing of U.S. journalist James Foley, Obama is seen as unlikely to deepen his near-term military involvement in either Iraq or Syria as he seeks to avoid becoming embroiled in another messy Middle Eastern conflict.

But U.S. officials say they have not ruled out escalating military action against ISIL, which has increased its overt threats against the United States since the air campaign in Iraq began.

"We haven't made a decision to take additional actions at this time, but we truly don't rule out additional action against ISIL if it becomes warranted," Ben Rhodes, a senior Obama aide, told National Public Radio earlier on Thursday, using another name for ISIL.

General Martin Dempsey, chairman of the U.S. Joint Chiefs of Staff, said officials were worried about the possibility that European or U.S. nationals, radicalized after fighting in Iraq or Syria, would return to their home countries.

Dempsey suggested ISIL would remain a danger until it could no longer count on safe havens in areas of Syria under militant control.

"This is an organization that has an apocalyptic, end-of- days strategic vision and which will eventually have to be defeated," Dempsey said.

"To your question, can they be defeated without addressing that part of their organization which resides in Syria? The answer is no. That will have to be addressed on both sides of what is essentially at this point a non-existent border."