Patrick Maxwell is a former Marine who returned to Iraq in 2014 to fight with Kurdish forces against the Islamic State.
“We patrolled every day, got shot at, mortared, hit by I.E.D.s, one of my friends was killed,” said Mr. Maxwell, a former sergeant who deployed in 2006 to Anbar Province. “But I never saw the enemy, never fired a shot.”
With the Islamic State, also known as ISIS or ISIL, hoisting its black flag above many Iraqi cities that United States troops spent years working to secure, he saw a second chance. He connected with a Kurdish military officer online, packed his body armor, some old uniforms and a faded green ball cap with a Texas flag patch on the front, and flew to Iraq.
Within days, he was on the front lines as a volunteer fighter with Kurdish security forces, known as the pesh merga, in northern Iraq, peering through a rifle scope at Islamic State fighters as bullets whizzed past.
“I may not be enlisted anymore, but I’m still a warrior,” said Mr. Maxwell, who left the Marines with an honorable discharge in 2011. “I figured if I could walk away from here and kill as many of the bad guys as I could, that would be a good thing.”
Mr. Maxwell is one of a small number of Americans — many of them former members of the military — who have volunteered in recent months to take up arms against the militants in Iraq and Syria, even as the United States government has hesitated to put combat troops on the ground. Driven by a blend of motivations — outrage over the Islamic State’s atrocities, boredom with civilian life back home, dismay that an enemy they tried to neutralize is stronger than ever — they have offered themselves as pro bono advisers and riflemen in local militias.
“More than anything, they don’t like ISIS and want to help,” said Matthew VanDyke, an American filmmaker who has spent time this winter with four American veterans covertly training a militia of Assyrian Christians in northern Iraq to resist the Islamic State. He is now recruiting more veterans to help, though late in February, the American Mesopotamian Organization, a California-based nonprofit that helped fund the militia, broke ties with him.
In a phone interview from Iraq, Mr. VanDyke said that many veterans spent years honing combat skills in war only to have them shelved in civilian life and that they are eager for a new mission.
“A lot of guys did important stuff overseas and came home and got stuck in menial jobs, which can be really hard,” he said. “We offer them kind of a dream job, a chance to do what they are trained to do without all the red tape and PowerPoints.”
While the United States authorities have tracked and prosecuted citizens who try to join the Islamic State, it is unclear how they will respond to Americans’ fighting the group, especially since some Kurdish militias in Syria have ties to groups the State Department classifies as terrorist organizations.
Behind the scenes, American officials have pressured the pesh merga to keep Americans out of the fight, according to American military veterans who have been in Iraq. After being contacted by The New York Times, the pesh merga released a statement saying it would no longer accept foreign volunteers. Other militias are still accepting Westerners.
The fight against the Islamic State is not the first time Americans have joined wars independent of their military. Pilots flew for the Allies in World War I and II long before the United States officially declared war. In the Spanish Civil War in the 1930s, Americans formed a contingent of more than 2,500 troops.
The decision to fight the Islamic State carries risks. Beyond being killed, captured or kidnapped and held for ransom, Americans could also get caught fighting with a group that is viewed as a terrorist organization by the United States government. John Walker Lindh, for instance, joined the Taliban to fight other Afghans during that country’s civil war but then was captured by American forces during the invasion after the Sept. 11, 2001, attacks. He was sentenced to 20 years in prison for a list of crimes including conspiracy to murder American citizens.
“These war zones are often foggy, and tough to tell friend from foe,” said Neil MacBride, a former United States attorney who has prosecuted similar cases. “U.S. citizens could risk running afoul of U.S. material support to terrorism laws if they took up with the wrong group.”
Mr. Maxwell said he went to Iraq in part because little was keeping him here.
After a solid career in the military, which included guarding the president at Camp David and training troops, he left the Marines in 2011. He drifted from job to job, working construction, tending bar and pedaling a bicycle taxi. He also worked as a security contractor guarding an American Consulate in Afghanistan, but left after seven months.
Last fall, as the Islamic State escalated attacks in Iraq, he was buying and selling houses in Austin when it dawned on him that he wanted to return to Iraq to find the enemy that had eluded him nearly a decade before.
Fearing that joining the wrong militia could get him in trouble with antiterrorism laws, Mr. Maxwell contacted a lieutenant in the pesh merga through Facebook and offered his services.