This town near the Iranian border has long been a symbol of Kurdish resistance. It is best known as the site of a gruesome chemical-weapons attack by Saddam Hussein in 1988.
These days, residents say, it is increasingly known for something else - although few want to talk about it.
Kurdish authorities say a small contingent of Kurdish youths - about 150 in all, about a third of whom are from Halabja - has in recent months joined the Islamic State of Iraq and the Levant (ISIL, also known as Isis), which has seized a vast swathe of Iraqi territory.
The young men's allegiance to the extremist group represents a potential danger for the Kurds, who share the jihadists' resentment of Iraqi Prime Minister Nouri al-Maliki's Shiite-dominated government but are wary of the extremists massed near their territory. The Kurds have hoped to keep their largely autonomous region in northern Iraq from being entangled in the country's increasingly bloody conflict.
Some Kurdish intelligence officials fear that with ISIL's gains, more local youths will join the jihadists and that the radical ideology could creep beyond Arab Iraq and into Iraqi Kurdistan, which has so far remained an oasis of calm and order.
The presence of Kurdish fighters in the militant group highlights how effectively ISIL's recruitment efforts are reaching disenfranchised youths across Iraq's ethnic divide. Most Kurds are Sunni Muslims, like the insurgents, but have their own language and culture.
A top local intelligence official in Halabja, who spoke on condition of anonymity because he was not authorised to speak to the media, said ISIL was already operating "cells" inside the town, appealing to bored and underemployed young people.
Most of the 52 local men and boys who had left Halabja in the past year and a half to fight in Syria had been recruited by ISIL, he said.
One local man, Mariwan Hallabji, had become an ISIL commander and currently served on a front line against Kurdish peshmerga security forces outside the city of Kirkuk, the official said.
"How do we guarantee that when they're done fighting the Shiites, they don't start waging a war against the Kurds?" the intelligence official said.
A little over a decade ago, Islamist radicals allegedly tied to al-Qaeda had a base in Halabja and fought against the Patriotic Union of Kurdistan (PUK), one of the two major Kurdish political movements, before US forces bombed the Islamists' bases during the 2003 invasion of Iraq.
Halabja, although relatively far from the front line between Iraqi Kurdistan and ISIL-held territory, was particularly vulnerable to losing its sons to the radical group, local officials and residents said.
The town lacked jobs and educational opportunities and had a history of militant resistance to the Arab government in Baghdad, residents said. Almost every family has a "martyr", either from the Kurds' struggle for independence or from the chemical weapons attack in 1988 that killed thousands. Hussein's forces attacked the town because of its sympathy for Iran during the Iran-Iraq war.
The situation has deteriorated since Maliki's government, in a dispute with the Kurdistan regional government, slashed the Kurds' budget six months ago, halting the payment of salaries to many workers.
"People here are graduating from high school, and they think they have no future," the intelligence official said. In the Western world, depressed teenagers committed suicide, he added. "People here join Isis - which is also basically suicide."
"Z", whose name is being withheld at the request of his family, would seem an unlikely recruit for ISIL, which has enforced a brutal interpretation of Islamic law, executing hundreds of Shiites and others in its bid to establish an Islamic caliphate that spans Iraq and Syria.
"He had a motorbike. He had a girlfriend. He had lots of friends," Z's brother-in-law said with a bitter laugh one recent night, as the family sat on the hard, thinly carpeted floor of their modest living room.
But Z's family thinks he was enticed by the extremists' slick social media campaign and by local recruiters.
Photos on Z's sister's cellphone show a grinning 16-year-old boy with a fluffy black "faux-hawk", the latest hairstyle craze.
His family said Z was not especially religious and was never particularly interested in going to the mosque. But in mid-May, he suddenly left Halabja with his best friend to join ISIL in Syria, his relatives said. "In one week, he changed completely," his brother-in-law said.
After the ISIL advance into Iraq, Z was now with fellow militants in the northern Iraqi city of Mosul, the family said. In a few phone calls, he has told his family that he was "following the teachings of the Koran", they said.
Two intelligence officials, as well as residents of Halabja, said Kurdish authorities had allowed young people such as Z to leave the region, in part because they thought it was safer without them. "They want them out of here. They don't want the bomb to explode in their hands," said a second intelligence official, who also spoke on the condition of anonymity.
In one recent instance, the bomb nearly did go off.
In late May, a young Kurdish man from Halabja who had recently returned from fighting with ISIL in Syria was apprehended by local security forces as he tried to enter a Shiite shrine in the Kurdish city of Sulaymaniyah carrying a backpack containing explosives, officials said.
Friends and relatives of a few other young men who have returned say the authorities have sought to put them through a lengthy reverse "brainwashing" process to persuade them to abandon their radical beliefs. The men are then heavily monitored.
"Those who come back are taken through a very intense process to ensure that they have left those thoughts behind," said Fazil Basharati, a Halabja local and former member of parliament from the Kurdistan Democratic Party.
Relatives of young men who are either fighting with ISIL or have left the group and returned said that Kurdish security forces had ordered them not to speak about their family members' ties to the group because it drew attention to the issue.
"They don't let them talk about it," said a 24-year-old man in Halabja who grew up with the Kurdish member of ISIL who tried to blow up the shrine in Sulaymaniyah. The 24-year-old man said two of his other neighbours had joined the extremist group in Syria, only to be captured and returned by Turkish Kurds who are fighting with Syrian insurgents opposed to ISIL. The man said one of his cousins was killed fighting in Syria four months ago.
Z's brother-in-law recently implored the 16-year-old over the phone to return to his mother and sister. "I said, 'What if someone tries to harass them?' He told me: 'We have plenty of Isis people in Halabja to stop them'."