The wannabe Islamic State fighters that have been leaving France, England, and other European countries in droves, responding to savvy recruiting efforts on social media and the promise of life in the caliphate, are not the only ones who are making their way to Syria and Iraq to fight a war almost everyone there wishes they could flee.

As the IS has expanded its grip on Iraq, coming threateningly close to Iraqi Kurdistan, the region's military forces — the Peshmerga — have responded with a resistance that has put to shame the Iraqi forces, many of whom fled as the Islamists advanced.

Now, with help from the air from Western allies, they have pushed back against IS advances, and rescued thousands of Yezidis and other minorities fleeing for their lives. But they have also faced big losses.

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In Syria, the Kurdish popular protection units — or YPG — have struggled to defend their enclaves, more recently joining hands against the IS with other rebel groups. Turkish Kurds also crossed both borders to lend a hand to their brethren in Iraq and Syria.

But as the IS moved closer — taking over several Kurdish villages in Syria over the last week — Kurds long established in western Europe have started to travel back to the region to defend their homeland.

Thousands of Kurds live in Europe, mostly having arrived as refugees at different moments in the last few decades — from Turkey and Iran first, and more recently Iraq and Syria. Now, some are choosing to go back.

"The trend that's been talked about in the last several months is Europeans traveling to fight with ISIS," Shwan Zulal, director of a UK-based risk analysis firm that focuses on Iraqi Kurdistan, told VICE News. "But given that the Kurdish authorities have had some setbacks, many Kurds from Europe, when they see their country or region at risk from ISIS, they feel patriotic and sometimes go back."

The numbers, Zulal admitted, are nowhere as sensational as those of Europeans who have gone to join ISIS — more than 2,000, according to recent estimates.

"It's in the low hundreds, a couple hundred people max," Zulal guessed, though he admitted it's difficult to know, as many Kurds spread across Europe hold dual citizenship with Iraq or Syria.

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Most European Kurds known to have joined the resistance against the IS have done so in Iraq, where the Peshmerga continue to keep the group's advance under relative control.

But the arrival of inexperienced fighters from Europe is not always easy, especially in Syria, where many get stuck on the Turkish border — or even useful — particularly in Iraq, where the Kurdish resistance to the IS is fairly organized and made up of experienced troops, some observers noted.

'We are not encouraging civilians who want to come back and join the Peshmerga forces. But we are also not creating barriers for them.'

"The Kurdish Peshmerga are quite regulated now, it's not that easy to go and join a militia and fight, you have to go through some checks, and through the authorities in Kurdistan," Zulal said. "Now they have some sort of unit for volunteers, whether they come from abroad or they are local, but usually most are local."

But Halgurd Hikmet, general director of the Peshmerga Ministry in Iraq, told VICE News that all volunteers — local and foreign — are welcome and appreciated, though the ministry does not actively recruit them.

"They haven't been a burden or trouble, the opposite, they have been a really good backup for the Peshmerga," he said. "And if any of these volunteers are injured or martyred, we treat them as Peshmerga and give them all rights."

But the force, which Hikmet said numbers 150,000 troops, needs weapons more than anything else, he added.

"We are not encouraging civilians who want to come back and join the Peshmerga forces," he said. "But we are also not creating barriers for them."

The people who are encouraging Kurds to come fight the IS — from Turkey or anywhere else — are Kurdish leaders in besieged Syrian towns.

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The latest IS advances there have sent thousand of Syrian Kurds fleeing into Turkey, and local leaders crying for help.

Thousands of residents of the predominantly Kurdish town of Ayn al-Arab, also known as Kobani, in northern Syria fled their homes towards the Turkish border as Islamic State fighters closed in on the city.

"We are calling upon those from Kobane living outside to come back to Kobane, center of honor and bravery, in order to protect their own people," said Anwar Moslem, the leader of Kobane, or Ain al-Arab, a Kurdish canton in Syria under siege by the IS. "We are calling on all Kurdish people, especially those from Northern Kurdistan [Kurdistan of Turkey), to head towards Kobane and protect their own brothers and sisters again, like they had done it before."

"If ISIS seizes Kobane, they will soon head to Turkey," he added.

His calls were followed by those of Iraqi Kurdish president Masoud Barzani, across the border.

"I call on the international community to use every means as soon as possible to protect Kobani," he said in a statement. "IS terrorists... must be hit and destroyed wherever they are."

Turkish Kurds have been responding to the calls for help of their Syrian counterparts across the border — despite attempts by Turkish authorities to stop them — as well as other fighters — to cross into Syria.

The involvement of Turkish Kurds — and the PKK in particular — presents an interesting dilemma for European governments, as the group is listed as a terrorist organization in the EU and the US.

So far, European governments have turned a blind eye to their citizens traveling to Iraq and Syria to join Kurdish troops there — a very different response to the one they have to IS supporters.

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Dutch officials said that Dutch Kurds are not being prevented from joining the Peshmerga and won't be prosecuted for doing so, unless they commit war crimes, the AP reported. But joining the PKK, they added, would be a crime.

Other countries seconded that attitude — suggesting that the influx of Europeans traveling to the region to join the conflict was alright with authorities so long as they chose to fight on the "right" side of the war.

"Our focus as a security service will be more on groups like IS and not people going to defend areas against the IS," a Norwegian security officer told the AP.

But in some countries like the UK and France, which have gone to great lengths to stop their citizens from joining the IS — including by stopping them at the airport, and, controversially, stripping them of their passports — the differential treatment afforded to Kurds is seen as more problematic.

"UK laws prohibit engaging in war in other countries, but so far there haven't been any warnings from the government," Zulal said. "The reality, I think, is that authorities are not concerned. They are concerned with ISIS more than with Kurds traveling to fight ISIS."

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If anyone has any complaints about the differential treatment, it's probably those Europeans who are not being stopped from joining the caliphate, he said.

"The Kurds are actually helping the coalition in some way," Zulal said. "If you're a Western ISIS member and you have a Western Kurd who goes and defends his homeland, I don't think you really have an argument to say 'Oh, why should he go and not me?'"