A prominent militant who fought with Russian-backed separatists in Ukraine and participated in far-right European politics recently completed U.S. Army training and is serving in an American infantry division in Hawaii, according to Army and other records.

Guillaume Cuvelier, 29, shipped for basic training in January and graduated as an infantryman at Fort Benning, Ga., the records show. In a short exchange with The Washington Post, Cuvelier confirmed that he was actively serving in the U.S. Army.

With his well-documented history of espousing extreme right-wing views and his role in an armed group backed by a U.S. adversary, Cuvelier’s ability to join the Army raises questions about the recruitment process and whether applicants are thoroughly screened before they are able to enlist.

Born and raised in France as a dual French and American citizen, Cuvelier spent his formative years alongside French ultranationalists before picking up a Kalashnikov in eastern Ukraine in 2014, according to social media posts, a documentary in which he was featured, and accounts from people who knew him. A year later he fought with the Kurdish peshmerga in northern Iraq before coming back to the United States.

Following inquiries by The Post, the military has “begun an inquiry to ensure the process used to enlist this individual followed all of the required standards and procedures,” said Kelli Bland, a spokesman for the U.S. Army’s recruiting command, in an email.

In Ukraine, Cuvelier, also known as Lenormand, fought for the Russian-backed Donetsk People’s Republic, the breakaway state subject to U.S. government sanctions and labeled terrorist by the U.S.-allied government in Kiev. Cuvelier’s service with the group appears to be in direct violation of a March 2014 executive order that was applied to the republic that June. The order prohibits U.S. citizens from assisting by way of “funds, goods or services,” any of the sanctioned entities covered by the order, opening up Cuvelier to possible federal prosecution.

The U.S. Army often forbids those who display “extremist views or actions” from entry, said Lt. Col. Randy Taylor, a spokesman for the Army’s Department of Manpower and Reserve Affairs, in an email. Taylor added that “if an Army official determines an applicant has the potential for meeting Army standards, the official may in exceptional cases allow those who have overcome mistakes and past conduct, made earlier in their lives, to serve their country. However, in many cases a history of gang or extremist activity is disqualifying.”

Cuvelier said he has changed.

“The [U.S.] army is my only chance of moving on and cutting with my past,” Cuvelier said in a text message. “I realized I like this country, its way of life and its Constitution enough to defend it.”

“By publishing a story on me, you are jeopardizing my career and rendering a great service to anyone trying to embarrass the Army. My former Russian comrades would love it. … so, I please ask you to reconsider using my name and/or photo.”

As a dual citizen, Cuvelier would be subject to more extensive background checks if he had sought an Army position requiring a security clearance, but he did not need one as an infantryman, Bland said. If Cuvelier had no outstanding criminal activity in the United States and didn’t discuss his past, there would have been no reason to bar him from enlisting, she added.

Cuvelier grew up in Rouen, France, and graduated from university there in 2009, according to his Facebook profile, which has since been deleted. His younger brother, Gabriel Cuvelier, said in a series of texts that his family is “fairly complicated,” without providing details, but that Cuvelier had always been kind and peaceful and “never sought attention.”

Online documents show Cuvelier was an active member in the Party of France, a political body that splintered from Marine Le Pen’s National Front, in 2010. Jean-Yves Camus, a French analyst who studies the far-right and has tracked Cuvelier, compared the Party of France to an American white-nationalist group called “National Vanguard.”

Cuvelier was also part of the neo-fascist group “Troisième voie” and an identity movement called the “Young Identitarians,” according to Anton Shekhovtsov, a visiting fellow at the Institute for Human Sciences in Vienna, who focuses on right-wing movements across Europe and has written extensively about the Ukraine conflict.

Cuvelier’s younger brother couldn’t explain how his older sibling first got involved with France’s far right, but said “his views led him to meet people.”

“I believe that when he was in France, he sort of saw that no ‘honest’ way of going about ‘politics’ was possible, so he decided to take action differently,” the younger Cuvelier said in a text. “That’s all I can say.”

Upon arriving in Ukraine in the middle of 2014, Cuvelier helped start a French-Serbian foreign fighter unit called the “Unité Continentale.” The group’s manifesto on its Facebook page states that NATO is “a terrorist military alliance” and that France is “a slave of the American Empire.” The group’s views are based on an ideology called “continentalism” espoused by the anti-Western Russian political scientist, Alexander Dugin. The group’s page also has multiple posts from July and August 2014 that solicited donations directly to Cuvelier’s bank account in France.

Posted by Unité Continentale on Monday, August 25, 2014

“Russia embodies a power. A power of resistance, what we want to bring back to the West. A society structured around tradition, family, patriotism,” Cuvelier says, explaining his motives for joining the separatists during the 2015 documentary titled “Polite People.”

Cuvelier eventually split from Unité Continentale, according to the documentary on Western militants who joined the fight in eastern Ukraine. In the film, Cuvelier’s band of fighters adopts the name “Team Vikernes” after the Norwegian black metal artist, self-proclaimed Nazi and convicted murderer, Varg Vikernes.

Videos posted on the Team Vikerne’s page show its members firing around the Donetsk airport, the site of a bloody close-quarters fight between Ukrainian troops and separatists in the winter of 2014. Cuvelier declined to answer any questions about his service in eastern Ukraine and when pressed over a series of text messages said, “I was never really in DPR. It was a hologram.” He declined any further comment.

In the documentary, there is a still picture of Cuvelier with a medal pinned to his chest standing shoulder to shoulder with Igor Girkin (who was the commander of the separatists during the summer of 2014). It appears in the documentary that Cuvelier may have been honored with the medal in Moscow in 2015.

Girkin has been sanctioned by the U.S. Treasury for his role with the separatists and on a Russian radio talk show admitted to having looters executed. He is also accused in a U.S. lawsuit of orchestrating the shoot-down of Malaysian Airlines flight MH 17 over Ukraine in July 2014, killing nearly 300 people.

Following his time in Ukraine, Cuvelier traveled to northern Iraq in 2015 and set up another unit of foreign fighters, this time allied with the Kurdish Peshmerga.

The group, called Qalubna Ma’kum, was located near Daquq in northern Iraq from the end of 2015 to mid-2016.

Rick Findler, a U.K.-based photographer who followed Qalubna Ma’kum for 10 days said, “They thought they could just show up with guns and start fighting. Instead they just sat in a room for months.”

The Peshmerga eventually forced Cuvelier to leave Iraq after an incident in which he was accused of beating an American volunteer with a rifle, according to Heloisa Jaira, a Peshmerga medic, who treated the victim.

Weeks later, he arrived in the United States.

Andrew Roth in Moscow contributed to this report.