A Brooklyn man traveled overseas to join terrorist groups linked to al Qaeda and to kill US troops with the aim of dying a martyr for his radical Islamic faith, federal prosecutors said at the start of his trial yesterday.

Betim Kaziu, 23, is an American who was arrested in 2009 and accused of plotting to join an al Qaeda-affiliated group and obtain automatic weapons to kill Americans serving in Afghanistan, Iraq and the Balkans.

“Al Qaeda and other foreign terrorist organizations have put out a call to arms,” said assistant US Attorney Seth DuCharme during opening arguments in Brooklyn federal court. “Betim Kaziu answered that call.”

A search of Kaziu’s laptop turned up training videos and lectures from terrorists such as Osama bin Laden, DuCharme said, along with a series of personal communications through e-mail, videos and social-networking sites that underscored the seriousness of his pursuit.

But Henry Steinglass, Kaziu’s attorney, rebutted prosecutors’ implication that the videos were anything more than Kaziu and his friends “fooling around.”

“Evidence will show that there are other interpretations” of the videos and other communications, Steinglass said. “Innocent interpretations.”