A permanent U.S. resident arrested in the Bosnian capital of Sarajevo abandoned the United States in 2013 to join the Islamic State group and cheer on suicide bombers while recruiting and spreading propaganda on the internet, authorities said Wednesday.

William F. Sweeney Jr., head of the New York FBI office, said Mirsad Kandic expressed a desire to travel overseas to kill or maim U.S. military forces long before he used fake documents to overcome a no-fly designation in December 2013 and travel to Turkey. From there, he joined the terrorist group, Sweeney said.

The former Bronx and Brooklyn resident was extradited Tuesday from Bosnia and Herzegovina to face a six-count indictment including charges of conspiracy and providing and attempting to provide support to the Islamic State. He has been detained since his July arrest in Sarajevo.

"Kandic is now back in New York, no longer living freely among us, but rather in federal custody to face justice," Sweeney said of charges that carry a potential for a life prison sentence.

James Branden, a lawyer for Kandic, said he had no immediate comment. His client pleaded not guilty in Brooklyn and was detained without bail.

Acting U.S. Attorney Bridget M. Rohde said Kandic recruited others to join the Islamic State group, "swelling their ranks and helping them commit terrorist acts such as suicide bombings."

A government detention memo listed deadly attacks carried out by Islamic State supporters, including 2015 shootings in Garland, Texas, and San Bernardino, California, along with a June 2016 nightclub shooting in Orlando, Florida, and numerous attacks overseas, but there was no mention of a truck that swerved through a bike lane in Manhattan pn Tuesday, killing eight people.

The government said Kandic began as early as 2005 to express a desire to travel to Pakistan, Afghanistan and elsewhere in the Middle East to fight U.S. forces in martyrdom missions.

"By late 2013, the defendant began trying to realize those objectives," prosecutors wrote.

Authorities said Kandic recruited individuals from the United States, the United Kingdom, Australia, and elsewhere to travel to Syria and Iraq and join the group's battles. They said he told an associate online that he worked in Turkey in the Islamic State's border office as part of a team that conducted background checks of foreign fighters who wanted to go to Syria.

In court filings unsealed Wednesday, prosecutors said Kandic's voice was captured in a recorded voice memo to an associate saying he had sent over 20,000 fighters to a region that included Syria.

Sweeney said Kandic assisted Jake Bilardi, an 18-year-old Australian citizen who died in a suicide bomb attack west of Baghdad in March 2015.

In court papers, prosecutors said Bilardi told Kandic through a Twitter message shortly before the attack that he "just went to look at my target today for my operation."

"May Allah reward you immensely," Kandic was quoted as responding. Prosecutors said he later added: "May Allah make ... inner organs implode."

Prosecutors said Kandic disseminated terrorism propaganda through over 100 Twitter accounts.