Fazel Hawramy in Kirkuk and Raya Jalabi in New York

From his muddy outpost on the front line in North Iraq, Grim can see the black flag of the Islamic State snapping in the wind just 500 metres away.

The 52-year-old Boston native – who several months ago found his way to a peshmerga base south of Kirkuk – sits in a crude breeze-block shelter, surrounded by mud and dirt, gunfire crackling in the background.

“We are fighting a scourge,” said Grim, who did not want to disclose his real name. “We are fighting murderers and rapists: people who burn people in cages, people who behead people. This is not a civilised army. They are animals.”

Grim said he had been moved to leave behind his life in the US and take up arms after reading about the militant group’s persecution of Yazidi and Christian civilians. “I have two kids and a beautiful woman at home,” he said. “She knows I’m here and she’s not happy about it, but she understands.”

He is just one of dozens – and possibly scores – of Americans who have traveled thousands of miles to northern Iraq to fight alongside Kurdish Peshmerga forces and Christian militias and against Isis. Some of the volunteers are civilian with no military experience; others are veterans of the US interventions in Iraq and Afghanistan; most have washed up in a war zone with little more than a one-way ticket and a few contacts made through Facebook.

These Americans have joined hundreds of western volunteers reported to have trickled into Iraq and Syria since Isis declared its caliphate last year. Their arrival has provoked mixed reactions on the ground: militia groups defending the Christian minority have expressed gratitude; some Kurdish fighters told the Guardian they would rather see the US government send guns and heavy artillery.

But the influx of American volunteers does not look set to end any time soon. Several new groups, predominantly of military veterans, have emerged, hoping to provide a more organized framework for those willing to risk their lives in a foreign war.

Several months before setting off from Boston, Grim began researching the Peshmerga online and came across two members of the Asayish – Iraqi Kurdistan’s intelligence and security forces – on Facebook. Many Peshmerga fighters and members of the security forces are easy to find on social media: there are several Facebook pages run by members of the forces themselves, and many of them keep their social media accounts public, with their contact information on full view.

After looking at different Peshmerga profiles, Grim said he chose three people to contact individually. “I followed their activities and when I felt comfortable, I told them I wanted to come and fight with them. I was welcomed with open arms.” That was enough reassurance for Grim to get on a plane to Erbil.

Though he had no military background, Grim had worked in private security. He said ended up joining the peshmerga and was deployed to the frontline with several other foreign volunteers.

“In the beginning, it was a little slow making any advances, but now [the peshmerga] are starting to feel comfortable with us; they are taking us to combat,” says Grim, whose unit came under heavy fire from Isis last month.

That route to the Kurdish front lines after initial contact on social media seems typical among the American volunteers. Just as the Islamic State has exploited its aggressive online presence to recruit foreign jihadis, Kurdish factions – the Peshmerga in Iraq and the YPG in Syria – are now expanding their online recruitment efforts.

Kevin Williamson, a 20-year-old US soldier, has less than one month left before he officially leaves the army. The first thing he plans to do after leaving the Kentucky base where he has been stationed is to spend a month at home with dad. After that, he intends to head to Iraq to join the Peshmerga fighters and combat Isis.

Over the past few months, Williamson has connected with volunteer fighters overseas, both through Peshmerga FRAME – a network of English-speaking volunteers fighting with the Kurds in Iraq – and through the Facebook page of the YPG’s foreign recruitment arm, the Lions of Rojava, which, with more than 75,000 “likes” on the site, is the first port of call for many aspiring American fighters.

“When somebody posts, ‘Hey, how do I get over [to Iraq or Syria]?’ I’d basically contact them, I would vet them and make sure they are who they say they are,” Williamson said. Once he vetted the individuals, mostly military veterans, Williamson would “pass them to the proper channels”, either to Peshmerga or YPG contacts he has.

Williamson has helped several Americans make contact with Kurdish fighters. Of these, at least five are on the front line, with a sixth arriving last week.

By and large, those American volunteers who have fought for the Kurds have been individuals who have made their connections through social media. They have mostly traveled alone on self-funded missions. But several groups have recently sprung up to organize these disparate volunteers more systematically.

Veterans Against Isis is a group made up of US military veterans who intend to travel to Iraq to combat the extremist group.

“I was gripped with a passion to go,” said Sean, one of the group’s leaders. “So I threw up a website so I could find other people who would go with me, because I didn’t want to go by myself.” Soon, he had about two dozen veterans; most had served with the US military in Iraq or Afghanistan.

The group is getting ready to deploy to the Mosul area “within the next 90 days”, said Sean, who asked not to be identified.

“Our mission is just to support locals in Iraq and eventually Syria against Isis,” he said. “Most of us are Iraq war veterans. It is our intent to go and liberate Iraq and then to push into Syria.”

Another US-led organization, Sons of Liberty International (SOLI), has spent the last several months training Assyrian Christians in northern Iraq.

SOLI, a private contracting firm, was founded by Matthew VanDyke, an American filmmaker and former mercenary, who fought alongside Libyan rebels and was held by Gaddafi forces for six months in late 2011.

VanDyke said those experiences in Libya helped him understand the nature of the fight against Isis in Syria and Iraq, which, matched with his “disappointment” in the international community’s muted response to the crises in those countries, pushed him to found SOLI.

VanDyke, working with five former US military professionals, has so far trained 300 Christian fighters from the Nineveh Plains in northern Iraq, and, he claims, has “basically helped them build an army”.

“The Christian group is a persecuted group that has a lot of potential for becoming the best infantry group in the country,” VanDyke said. Despite having virtually no military background, “they’re highly motivated. They’re a group that’s been roughed up for a long time and nobody else is helping and nobody else will help.”

‘A powerful draw to go’

The possibility of fighting overseas against a clearly identifiable foe like Isis holds a strong appeal for military veterans who have often experienced a sense of alienation and “fantasy” about how the world works, said Adrian Bonenberger, a writer and former US infantryman who served in Afghanistan.

For many people who served in Iraq and Afghanistan as infantrymen, “their skill set was fighting and infantry,” Bonenberger said. “Then they came back [to the US] and they were qualified for very few jobs ... For those people, who felt alienated from society and didn’t have sufficient social networks there to help them back in, to reintegrate them into the civilian world, there must be – and I know because I’ve felt it myself – a powerful draw to go and use those skills that you’ve accumulated and those experiences you had overseas and the acclaim you got when you were fighting the enemy.”

Maria Fantappie, a senior Iraq analyst at the International Crisis Group, says this is partly due to how the conflicts in Iraq and Syria have been portrayed.

“Beside the military aspect, foreign fighters joining Kurds or other armed groups over the front line reveals the extent to which the rise of IS and the western governments’ response to it has forged the general perceptions that an epic struggle is ongoing between the forces of good and evil, modernity and backwardness.

“But beside far distant perceptions, on the battlefield this remains a conflict over resources, land and legitimacy, in which each side involved is equally eager to win the most and lose the least.”

In Duhok, Kurdistan, Lewis, a 24-year-old Texas native, is currently training with a Christian militia group to go and fight Isis. Lewis – or Tex, as he’s known in Duhok – said he was in the US marine corps until 2015 and fought in Afghanistan.

“My decision to come out here was like a calling,” Lewis told the Guardian. “I said, hey, you’re good at combat and people need you here; why not go? It had a lot to do with morals … What Isis did was very immoral by burning people and raping women.”

Despite these lofty ambitions, these western fighters have provoked a mixed reaction from the Kurds themselves.

Yusuf Sadiq, who has been with the peshmerga for the last 11 years, said: “I was very happy to see these foreign volunteers in Daquq, but I could not understand them. I am shocked to see these volunteers here trying to defend our homeland.”

Brigadier General Aras Abdulqader, the former head of a brigade under Saddam who is now head of an infantry brigade in Daquq, 25 miles (40km) south of Kirkuk, was dismayed that the volunteers were arriving unarmed. “It is important that their respective governments supply them with guns. The US has provided some assistance, but they need to speed up the process. We are ready to recruit and deploy these volunteers but … we need a proper military plan.”

The lack of weaponry and training of some of the volunteers has led to accusations that western fighters’ primary value and use has been as propaganda. This is certainly the case for the Lions of Rojava, who have used extensive images of western volunteers to help bolster their recruitment. YPG-branded images of the three western fighters (including a former British Royal marine and an ex-Australian soldier) who have died fighting with the Lions of Rojava have been widely disseminated.

“We have heard complaints that these volunteers have not seen real battle. But it is possible that if one of these volunteers dies, the US government will cause problems to Kurdistan, and why would the KRG (Kurdistan Regional Government) need this headache?” Sadiq said.

Officially, as far as the Ministry of Peshmerga is concerned, there are no foreign volunteers fighting with the Peshmerga in Iraqi Kurdistan.

“We do not accept any foreigners joining the peshmerga forces. We are an army, not a militia,” Jabar Yawar, the General Secretary of the Ministry of Peshmerga, told the Guardian last week. “The law does not allow us to accept these foreigners. Those volunteers who are now with the peshmerga forces have nothing to do with us. The ministry of Peshmerga is not responsible for them.”

But the ministry does not control the majority of the peshmerga fighters, and many of the brigades are still directly controlled by regional political parties, who are likely recruiting foreigners on their initiative.

Certainly the legality of these US citizens’ endeavors abroad has been called into question. Though fighting in a foreign country’s armed forces is not necessarily illegal, it is hardly encouraged.

“The US government does not support private US citizens traveling to Iraq or Syria to fight against Isis nor do we support any such activities,” said Michael Lavallee, a State Department spokesman.

Lavallee declined to comment on the legality of these citizens’ fighting abroad, but former State Department spokeswoman Jen Psaki said in October that she was not aware of any specific law which barred American citizens from fighting abroad, so long as they are not doing so with a foreign terror group.

Since neither the peshmerga nor the YPG feature on the US list of terror groups, Americans joining these efforts could be spared any legal conundrums. However, the YPG is overtly affiliated with the Kurdistan Workers’ Party, more commonly known as the PKK. Due to its history of armed opposition, the PKK is considered an terrorist organization by the US government, which could prove to be a complication for Americans returning home from the front lines.

These possible legal complications, however, are simply not going to stop Americans hoping to join the fight against Isis. According to Nusîcan Amudê, a media representative for the YPG, around 50 Americans have so far reached out to the YPG through its Facebook page. Amudê expects this number to swell by summer.

Back in Kentucky, Kevin Williamson is spending the days before his May birthday keeping up to date with daily developments in Iraq and Syria. Before summer’s end, Williamson, who has never before been deployed overseas, expects he will be fighting in Iraq.

“Do I think there’s other ways to help, other than picking up a rifle and going overseas? Yeah, there’s multiple ways. People can help fundraise, people can write their congressmen ... But my specific skill set? You know, I’m not really that great with anything other than being a soldier.”

additional reporting by Shalaw Mohammed

The Guardian