REUTERS - While illegally crossing the Iraqi-Syrian border, Canadian Peter Douglas was adamant that his incursion was for humanitarian reasons - to help the people of Syria.
Douglas is one of a growing band of foreigners to dodge authorities and join the fight against Islamic State militants who have killed thousands and taken vast parts of Iraq and Syria, declaring a caliphate in territory under their control.
Many of these fighters argue they are there for humanitarian reasons but they say their decision to take up arms to fight for the Syrian people will not be viewed as such by some.
"I want to fight the Islamic State, although it might be the last thing I do," said Douglas, 66, from Vancouver, as he prepared to board a boat crossing a remote stretch of the Tigris River.
"I know I have 10 years to live before I will start develop dementia or have a stroke so I wanted to do something good," he added, although he acknowledged that taking up arms was new on the list of jobs and occupations he has previously pursued.
So far an estimated few dozen Westerners have joined Kurdish fighters battling Islamic State in northern Syria, including Americans, Canadians, Germans, and Britons.
The Syrian Kurdish armed faction known as the YPG has not released official numbers confirming foreign or "freedom fighters" and academics say it's hard to assess the total.
But the number pales compared to an estimated 16,000 fighters from about 90 countries to join Islamic State since 2012, according to the U.S. Department of State figures.
The United Nations has warned extremists groups in Syria and Iraq are recruiting foreigners on an "unprecedented scale" and with a commitment to jihad who could "form the core of a new diaspora" and be a threat for years to come.
Fighting for a cause?
Western governments are closely monitoring foreign fighters but law enforcement agencies are acting differently towards those joining Islamic State or those linking up with the Kurdish resistance whose motivations are far more diverse.
British Prime Minister David Cameron has made it clear there is a fundamental difference between fighting for the Kurds and Islamic State. British law stipulates fighting in a foreign war is not automatically an offence and depends on circumstances.
Two British military veterans, Jamie Read and James Hughes, returned to England last month after several months with the YPG, saying they were fighting for "humanitarian purposes", and no action has been taken against them on their return.
They signed up outraged by a series of chilling videos showing the murders of two U.S. journalists, a U.S. aid worker, and two British aid workers and by the plight of millions of Syrians caught between Islamic State and government forces.
British-based monitoring group, the Syrian Observatory for Human Rights, estimates in six months the radical Sunni group has killed about 1,878 people in Syria off the battlefield, mostly civilians.
More than 200,000 people have been killed in the Syrian civil war, which started when President Bashar al-Assad's forces cracked down on peaceful pro-democracy protests in 2011.
"We went there to help innocent people and to document the YPG struggle against ISIS," Hughes, 26, who spent five years in the British army, told the Thomson Reuters Foundation.
"We had a warm welcome home. Everybody thought we were heroes. They were proud of us. I also received hundreds of messages of people wanting to join the YPG," he said, adding he planned to return to Syria in coming months.
Still many foreign YPG fighters are concerned about legal repercussions when they return home so seek to stay anonymous.
"We might get in trouble with our governments," said one U.S. veteran who ensured all his financial and legal affairs were in order before heading to Rojava, the area controlled by the YPG in Syria.
Many are concerned how the media portrays them at home and wanted to clarify they are volunteers, not mercenaries. They say they are not paid but are there as they believe in the cause.
Many have some military experience and have signed up to the battle through contacts on Facebook.
Lorenzo Vidino, an analyst at the Institute for the International Political Studies in Italy, said foreign fighters might argue they are joining the battle against Islamic State for the good but they were not effective militarily.
"Westerners joining the YPG are a very small phenomenon especially if compared to Islamic State. The IS recruitment machine works better and you can see evidence of that in terms of numbers," he told the Thomson Reuters Foundation.
U.S. fighter Dean Parker, 49, joined after watching video footage of the blitz on Sinjar in northwest Iraq in August when Islamic State militants killed or captured thousands of minority Yazidis.
"I saw the fear and terror on this child eyes who was looking directly at me through the camera ... I never been moved by anything like that in my life," he said in an email exchange, one of several foreign fighters from Syria interviewed on location, by email or by phone in November and December.
Canadian-Israeli woman Gill Rosenberg, 31, from Tel Aviv, said in a recent interview with Israel Radio that she decided to join the YPG for humanitarian and ideological reasons.
But not all foreign fighters are motivated by the same cause.
Jordan Matson, 28, a U.S. army veteran from Winconsin who joined the YPG about four months ago, said he joined because he was running away from a "civilian" life he didn't really like.
"Here, instead, everything makes sense," he told the Thomson Reuters Foundation in a YPG base near to Derik, a town in Syria's northeastern Kurdish region.
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