A video showing a large armed convoy of the Jabhat al Nusra militant group entering Khan al-Sabeel, a city on the Homs-Aleppo highway, emerged online on Tuesday.
The high-quality footage, uploaded by a group associated with al Nusra,shows a parade of vehicles and heavy weaponry travelling through the town heading north and suggests that the fighters are making their way, as Kurdish PKK military leader Cemil Bayik has warned, to a Kurdish enclave of Afrin within the Aleppo Governorate.
Bayik, the top PKK field commander, told the Independent that over a million Kurds, including 200,000 refugees lived in Afrin and are in danger.
"They are approaching its borders," Bayik told the newspaper. "They are calling villagers by telephone, saying, 'Runaway or we will kill you.' Like ISIS, they use psychological war, first creating panic among the people and then attacking."
Syrian government forces withdrew from Afrin in 2012 and the Popular Protection Units (YPG), the Syrian Kurdish fighters, have been in charge of the city since. Like Kobane, which has been besieged by the Islamic State for more than a month, Afrin is one of three Kurdish regions declared autonomous from the Syrian government earlier this year.
Hevi Mustefa, the leader of Afrin's local government, echoed Bayik's warning during a visit to the Turkish capital Ankara last week. "Afrin is surrounded by Nusra, we're ready to defend ourselves," she told Reuters.
However Mustefa has also reached out to Western governments and neighboring Turkey for help, saying that they want to avoid another Kobane.
Air strikes by a US-led coalition and efforts by the Iraqi Kurdish peshmerga fighters kept the Islamic State at bay. However, it was weeks before external forces intervened and, according to some, only when fighting looked set to disrupt Kurdistan's capital, Erbil, home of many US oil firms.
"We're grateful for the international community's efforts at Kobane, but it was late," said Mustefa. "We want support from them so that the situation in Kobane doesn't repeat itself."
Afrin has been targeted before. The Islamic State attacked the city in 2013, but was fought off. Al Nusra has held positions nearby for several months, and despite not launching a major offensive yet, their recent deals with other armed groups and this advance has triggered the Kurdish administration to believe they are gathering forces to attack.
Mustefa's calls for a bombing campaign if the expected attack from al Nusra happens have led to some contact with Western diplomats but calls to Turkey to open a border crossing to allow aid and trade into the region have been ignored.
The Kurds, and others, believe Turkey doesn't want to fight the Islamic State. Turkey is opposed to the autonomy of Syria's Kurds partly because they fear an uprising among the country's own 15 million-strong Kurdish population.
Their lack of aid for the Kurdish people could even escalate the historic conflict between Turkey and the Kurds, according to the Kurdish military leader.
"We don't believe that Turkey has abandoned its policy of attempting to eradicate the Kurdish movement. They can attack us at any moment," Bayik told the BBC. "So we are at a turning point. It is either peace or war. There is no middle way here."
There have also been several allegations that Turkey could be collaborating with the Islamic State.
Al Nusra is al Qaeda's Syrian wing and has been an effective rebel group in the fight in Syria's sectarian civil war against President Bashar al-Assad.
More recently, however, they have set their sights on other opposition groups including the Kurds, according to PKK leader Bayik and Afrin's Prime Minister Mustefa.
Further airstrikes on the Islamic State could force future collaboration between the militant group and anti-Assad rebel forces like al Nusra. A number of al Nusra fighters have already defected to ISIS since the strikes began.
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