The Justice Department under Attorney General Pam Bondi on Monday announced a U.S. citizen has been sentenced to 10 years in federal prison for joining ISIS. File Photo by Samuel Corum/UPI | License Photo

June 3 (UPI) -- A 49-year-old naturalized U.S. citizen who pleaded guilty to charges of fighting U.S.-led coalition forces as an Islamic State militant has been sentenced to 10 years in federal prison.

Lirim Sylejmani was sentenced Monday after pleading guilty in December to charges of receiving military training from ISIS, a designated foreign terrorist organization.

"The defendant will spend a decade in prison thinking about the betrayal to this country," U.S. Attorney Jeanine Ferris Pirro said in a statement.

Sylejmani and his family were detained by the Syrian Democratic Forces in Syria on Feb. 27, 2019, as coalition fighters made their final advances on ISIS' last caliphate in the country, which fell the next month.