By TIM ARANGO

BAGHDAD — Before war convulsed his hometown in Syria, Usaid Barho played soccer, loved Jackie Chan movies and adored the beautiful Lebanese pop singer Nancy Ajram. He dreamed of attending college and becoming a doctor. His life, to say the least, took a detour.

On a recent evening in Baghdad, Usaid, who is 14, approached the gate of a Shiite mosque, unzipped his jacket to show a vest of explosives, and surrendered himself to the guards. “They seduced us to join the caliphate,” he said several days later in an interview at a secret Iraqi intelligence site where he is being held.

Usaid described how he had been recruited by the Sunni extremists of the Islamic State from a mosque in his hometown, Manbij, near Aleppo. He said he joined the group willingly because “I believed in Islam.” “They planted the idea in me that Shiites are infidels and we had to kill them,” he said in the interview, which took place in the presence of an Iraqi intelligence official.

If he did not fight, he was told, Shiites would come and rape his mother.

He soon found himself in Iraq, but he quickly had misgivings and wanted to escape. His best chance, he decided, was a risky deception: volunteer to be a suicide bomber so he could surrender to security forces.