Via ABC News:
ISIS had recently threatened to kill U.S. journalist James Foley to avenge airstrikes the United States has conducted in Iraq, a senior U.S. official told ABC News.
The White House had been aware of the threat prior to the release of a video Tuesday night that appears to show the beheading of Foley and warns that militants will carry out a similar act against U.S. journalist Steven Sotloff, who went missing in August, the official said.
President Obama was briefed on the video aboard Air Force One Tuesday night as he returned to Martha’s Vineyard, Massachusetts, from Washington to resume his August vacation. The White House said the intelligence community is working to authenticate the gruesome video that allegedly shows Foley’s beheading.