More than half the men and women who have left the United States to join the conflict in Iraq and Syria may actually be battling against the Islamic State terror group instead of fighting for it.
That conclusion is based on a new report by the London-based Institute for Strategic Dialogue (ISD), as well as on court records and information previously shared by intelligence and law enforcement officials.
"That pathway is fairly well-trodden. The scale of it surprised us a little bit," said ISD Policy and Research Manager Henry Tuck, who co-authored “Shooting in the Right Direction: Anti-ISIS Foreign Fighters in Syria & Iraq.” ISIS is an acronym for Islamic State.
The report, released Tuesday, looked at the nationalities and motivations of foreign fighters who traveled to the region through the end of 2015 specifically to fight IS or other known terror groups. It found 114 of these fighters were from the U.S.
That figure alone would represent a sizeable chunk — almost 46 percent — of the approximately 250 Americans who, according to U.S. law enforcement officials and the intelligence community, have sought to take part in the overall conflict.
FILE - Young men chant pro-Islamic State slogans as they wave the group's flags in Mosul, Iraq.
But the percentage of American foreign fighters battling IS may be higher still — perhaps more than 50 percent — in large part because officials admit not all of the Americans who tried to go to Syria and Iraq actually made it.
In fact, statistics kept by the George Washington University Program on Extremism indicate as many as 47 would-be foreign fighters have been arrested in the U.S. and charged with IS-related offenses.
Authorities look the other way
While the U.S. has worked to cut down on the flow of foreign fighters to IS and other terror groups, travel to Iraq and Syria itself is not necessarily illegal, though the State Department advises against it.
"Private U.S. citizens are strongly discouraged from traveling to Syria to take part in the conflict," a State Department advisory warned earlier this year. "The U.S. government does not support this activity."
But the accounts of anti-IS foreign fighters included in the ISD report show few met with much, if any, resistance.
"We don't find too many stories of people getting stopped when they're leaving," said ISD's Tuck. "They might get taken aside and asked a few questions about where they're heading, what their plans are, but not too many people being turned away at the airport."
Some Americans fighting IS claim they have even been given verbal support from State Department officials in Iraq.
One such American, Matthew VanDyke, spoke with VOA via Skype in February 2015.
"This is really a full-time-plus job," VanDyke said at the time, describing his efforts to recruit U.S. combat veterans to offer specialized training to the Assyrian Christian fighters in northern Iraq. "It's going quite well."
State Department officials tell a different story.
"We do not endorse nonessential travel to Iraq by private U.S. citizens," one official told VOA when asked about VanDyke's claims.
FILE - Iraqi counter-terrorism forces advance their positions in Fallujah, June 22, 2016. Pockets of Islamic State fighters continue to hold neighborhoods along the north and west of the city.
Still, the ISD study found many anti-IS foreign fighters, whether from the U.S. or Europe, reported similar experiences.
"The advice will be, don't go, but it won't necessarily be explicitly illegal,'" Tuck said.
And while the anti-IS foreign fighters are not considered a threat to the homeland, there are reasons for U.S. officials to worry.
"We don't like any ad hoc foreign fighting," said Patrick Skinner, a former intelligence officer now with the Soufan Group, a New York organization that provides strategic security intelligence services to governments and multinational organizations.
"It's less the specific cause and more the general passion and armed militancy," he said. "The rising tide of extremism on all sides lifts all dangerous boats."
Who are they?
The report found a few primary routes to the conflict. One involved traveling through Turkey to Sulaymaniyah in Iraqi Kurdistan, where many of the anti-IS foreign fighters joined up with local forces. Other anti-IS foreign fighters reported traveling to Iraq via Europe or the Gulf States.
FILE - Fighters take a selfie while firing artillery against Islamic State militants in Fallujah, Iraq, May 29, 2016.
Many of the anti-IS foreign fighters also appear to have had an additional advantage. More than 30 percent were military veterans, many of whom had taken part in Western operations in Iraq and described the region "as a kind of second home," the report found.
Many of them also expressed a desire to "finish the job."
"They believe it is their personal responsibility to ensure the region's security if the international community and their own governments are unable to do so," the report said.
Researchers also found some commonalities between the foreign fighters battling against the IS terror group and those who seek to join it.
"These fighters fighting against ISIS have very different overall motivations," Tuck said. "But I think some of the more personal, some of the more individual, factors are quite similar in some ways."
"It might be a lack of belonging, a lack of purpose. They don't feel like they're doing enough with their lives," he said.
VOA's William Gallo contributed to this report.