U.S. intelligence, military officials and law enforcement have declined for months to discuss whether there are Americans that have joined Islamic State the extremist militant group that is blamed for the beheading of two American journalists.
However, now they have acknowledged that they believe one or more, but not more than a few have joined ISIS.
The officials said their opinion is based on analysis, on a number of recent arrests and the investigations of other U.S. citizens who were looking to join the group that currently is fighting in both Syria and Iraq against local government forces.
Officials believe that some Americans who have traveled to Iraq or Syria might have hooked up with ISIS. Officials from U.S. intelligence said that in general Western fighters not only Americans, are joining the group that is the most important at the moment and that is ISIS.
The officials emphasized that the U.S. does not have any specific intelligence that has identified an American as fighting with ISIS.
Other officials have said that small groups, no more than a dozen at one time, of Americans, are thought to be embedded with and fighting beside ISIS inside Syria and that some might have crossed the border into Iraq.
Previously officials had estimated that as many as 100 American have attempted to join different groups that were fighting to topple the President Bashar al-Assad regime in Syria and that approximately 70 have actually succeeded.
The difficulty factor in intelligence increases exponentially as soon as an Americans cross into Iraq or Syria.
Last week James Comey the Director of the FBI said his agency is not certain of the range of Americans that have traveled to Syria.
He said the number likely is over 100 but that could be 1,000 or even higher, but tracking them is next to impossible.
Three Americans were recently prosecuted for trying to join ISIS.
Adam Dandach who is 20 was arrested in LAX in July and told agents later he wanted to join ISIS.
Donald Ray Morgan who is 44 was arrested on August 2 on firearms violations. He had posted numerous messages online that were pro-ISIS.
Shannon Conley pleaded guilty last April to charges she was attempting to fly into Turkey on her way to join ISIS.