A 42-year-old Brooklyn man has been charged with providing and attempting to provide material support – including training, services and personnel – to ISIS in Syria, the Department of Justice announced Friday after unsealing a criminal complaint in Brooklyn federal court.

Ruslan Maratovich Asainov, a Kazakhstan-born, naturalized U.S citizen is alleged to have traveled to Istanbul, Turkey, in late 2013 before moving across the border into Syria where he became a sniper for the designated terrorist outfit.

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Asainov then rose through the ranks, prosecutors contend, to become an “emir” and oversaw the training of other ISIS recruits in the use of weapons. He is also accused of attempting to entice an informant working with the NYPD's intelligence division to join ISIS in Syria. Asainov told the informant he'd help get him a job, housing, food and $50 a month, according to the complaint. Asainov suggested the man bring his family, too, saying "even grandmothers are coming."

“The defendant, a naturalized U.S. citizen residing in Brooklyn, turned his back on the country that took him in and joined ISIS, serving its violent ends in Syria,” U.S Attorney Richard Donoghue stated, highlighting that he will now face justice in an American courtroom. “We hope countries around the world, including our European allies and partners, will likewise repatriate and prosecute their own citizens for traveling to support ISIS.”

In March 2015 he requested $2,800 from an informant to purchase a rifle scope, sending photographs of boasting about the group’s barbarity and declaring his wish to die on the battlefield. Instead, he was later detained by the U.S-backed Syrian Democratic Forces (SDF) and transferred into FBI custody on Wednesday.

“This arrest serves as a warning to anyone anywhere in the world who intends to support or conduct attacks on behalf of terrorist groups against the United States,” added NYPD Commissioner James O’Neill. “You will be brought to justice.”

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Asainov was detained without bail following a court appearance Friday. Defense attorney Susan Kellman said her client was "very pleasant, very forthcoming" but was reluctant to speak up when a judge asked him if he understood his rights.

"He answers to a higher authority," the lawyer said. "He says his ruler is Allah."

The Associated Press contributed to this report.