Intelligence officials are close to determining the identity of the
"We're not in a position to say exactly who this is," Ambassador Peter Westmacott said on NBC's "Meet the Press," adding: "I think we are close."
Experts in voice recognition are working to figure out the name of the Islamic State executioner who beheaded Foley and threatened to kill another American journalist, apparently in retribution for a U.S. bombing campaign against the group's forces in Iraq. A video of the killing was posted online last week.
If the United States does that, senior advisors have said, it will be because the United States perceives an imminent threat to Americans and U.S. national security interests. A major point of concern for the Obama administration is the apparent involvement of British citizens in the Islamic State, since they could travel easily in Europe and the United States.
In interviews on Sunday, Westmacott emphasized that the threat to the West from the Islamic State -- also known by its former acronyms, ISIS and ISIL -- is significant.
“People think that maybe as many as 500 British subjects have gone to Syria and Iraq for this cause of jihad," Westmacott told CNN's Candy Crowley on the program "
"And it's not a problem exclusive to the United Kingdom," he added. "We have got people from lots and lots of Western democracies who, unfortunately, are misguided enough to go to that part of the region and take up a cause which is a betrayal of all our values."
Westmacott said the British government is "putting a great deal into the search" for Foley's killer, who experts have said is probably younger than 30 and comes from London or somewhere nearby.
British newspapers reported Sunday that investigators are looking at several British militants believed to be in the Raqqa area of Syria, according to a London-based report from the Associated Press.
One of the possible candidates is a former rapper, the son of an alleged Al Qaeda operative extradited from the United Kingdom to the United States to face terrorism charges in 2012, the AP reported.