The possibility of militants sneaking into Europe as part of the huge flow of migrants from Syria and other countries has long worried governments and experts, but one viral picture claiming to show proof of a "migrant" Islamic State fighter isn't at all what it seems.
At first glance, the meaning of the pair of before-and-after photos on Facebook seems clear. In one, a bearded man wearing military gear and camouflage trousers holds aloft an assault rifle. In the next, a similar-looking man is clean shaven, wearing a T-shirt and a backpack. A caption says the photo was taken at the "Macedonian border".
"Remember this guy? Posing in ISIS photos last year - now he's a 'refugee'," the accompanying message reads. "Are we suckers or what!"
The picture, shared more than 70,000 times on just one Facebook account in recent days, was also spreading on Twitter, and attracted several thousand comments. The prospect of Islamic State (IS) fighters or other militants using the chaos of the current migrant crisis to sneak into European countries has been raised by EU officials and others. And IS operatives have bragged that they are sending militants across the Mediterranean via routes commonly used by people smugglers - although such claims are extremely difficult to verify.
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But if there are IS fighters posing as asylum seekers, this man is not one of them. In fact, for an asylum seeker, his identity is unusually well documented. His name is Laith Al Saleh, and last month he was the subject of a profile by the Associated Press news agency. He says that he was a Free Syrian Army commander, and that before the civil war he worked as a plasterer in his home city of Aleppo.
"About 70 percent of the city is destroyed ... In Syria, Al Qaeda want me, Daesh (Islamic State), the government - I fought them all. I don't care. Some people are afraid. I'm not," he told the news agency.
The two photos above appeared side-by-side in a photo montage on The Atlantic website shortly after the AP story was published. On that page Saleh is identified as a "Syrian former rebel commander", with no reference to the Free Syrian Army. The pictures were then circulated on Twitter and Facebook, where the details of Saleh's fighting in Syria became garbled.
The man who shared one of the most viral versions of the photo on Facebook tells BBC Trending that he took the photo off a Twitter feed and that he's sorry for getting the facts wrong.
"I copied the photo in good faith," says Peter Lee Goodchild. "I can only apologise for any hurt damage or offense that I've caused." He says he intends to apologise on Facebook, however he's been locked out of his account, and added that the photo was only one of his frequent posts on immigration, Islam and his opposition to the European Union.
The comments underneath one version of the pictures underscore the sharply divided debate online over how to deal with the sheer numbers of migrants arriving in Europe. Britain and other European countries have pledged to admit more Syrian refugees in recent days, following the publication of photos of the dead body of 3-year-old Aylan Kurdi, which seemed to crystallise public opinion. Meanwhile, Gulf states such as Saudi Arabia and Kuwait are being criticised by some for not taking in more refugees - there's more BBC News analysis of that story here.
"This picture posted by you is of a rebel fighter who fought ISIS. However why let the facts stand in the way of an ill educated swipe at brave people," one user commented on photo, while another countered: "Regardless of whether this man is a member of ISIS or not, I am quite certain there will be hundreds if not THOUSANDS of Islamic extremists who will find an easy passage into Europe amongst the genuine Refugees."
Blog by Mike Wendling
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