An increasing number women around the world are travelling to Iraq and Syria, believed to be supporting Isis or becoming jihadi brides.
Yesterday Security Intelligence Services (SIS) director Rebecca Kitteridge said the spy agency had seen New Zealand women making the journey.
They were "presumably" going to Iraq and Syria to be "jihadi brides", Prime Minister John Key said, although he admitted it was difficult to know for certain what the women did once they got inside the countries.
"Whether they are going to fight or whether they are going to support other fighters is not clear, but it is a real concern that they would go at all," he said.
So what is a jihadi bride, and how big is the problem?
Q: What are jihadi brides?
A: Women or teenagers who travel to Syria and Iraq to marry and support Isis extremists.
Q: How many women have travelled to Syria to join Isis?
A: It is believed more than 550 Western women have left their homes to join Isis fighters in Syria. Women from the US, Britain, Australia, Austria and now New Zealand are among those who have made the journey.
It is not known how many New Zealand woman have travelled to Syria and Iraq in support of Isis. Ms Kitteridge would not provide an exact figure yesterday, but said the number was less than a dozen.
Q: What makes them join?
A: The young women become attracted to what the Institute for Strategic Dialogue has called a jihadi, girl-power subculture. Their teen rebellion played out through a radical religiosity, which questions the world around them. Some have said they left as a way of "taking control of your destiny", to make their own choice, and walk away from an immoral society they see as sexualising girls from an early age.
They are often woo-ed online by Isis fighters in Syria, who build relationships with the impressionable teenagers, complimenting them, sometimes sending gifts, and making them believe they're in love with them. They boast about their lifestyle, claiming Isis is not how it is portrayed in Western media. They encourage the girls to adopt more conservative interpretations of Islam, and eventually to make the journey to Syria.
But Isis has also proven adept at appealing to different women, using "girl-to-girl" recruitment strategies to encourage other women to join the caliphate -- such as Scottish woman Aqsa Mahmood, who left Glasgow in November 2013 and is now considered one of the most active recruiters of young British women to Isis.
Q: Who is targeted by Isis to join?
A: Many of the women who travel are single and young, research groups say, typically in their teens or early 20s - the youngest known was just 13. They differ in terms of socioeconomic background, ethnicity and nationality, but are often more educated and studious than their male counterparts.
In general, Ms Kitteridge said the kind of people who were at risk of being radicalised may have problems in their life, were not "your average person who's going out to work, or happily married or raising their kids". They would be disengaged in some way with productive life, she said. But significantly, they came from a range of ages and backgrounds.
Q: What is life like for the women who go there?
A: While the men tend to become fighters, less is known about the Western woman who join Isis. It's believed they are banned from combat, and are there to support the group's state-building efforts as wives, mothers, and recruiters.
However, blogs and social media accounts have given a glimpse of what life is like for the women who travel to Syria. While some posts are about the banal details of life - bad cellphone reception, bad shampoo and poor quality beauty salons - other comments complain about malicious gossip, being pestered by Isis fighters to remarry after their husbands die in battle, while others pose with guns in front of Isis flags and openly show their support for violence.
Earlier this year, in photographs posted to a Twitter account believed to belong to Melbourne woman Zehra Duman, several women are pictured standing under an Isis flag, leaning against a clean white BMW M5, wielding machine guns and dressed from head to toe in black Islamic dress.
However, other women tell a different story, describing the men of Isis as "monsters". Yazidi women have previously spoken out about being sold as sex slaves and raped multiple times a day, abused on a regular basis, including being tied up and gang-raped and burned with cigarettes.
Researchers say life on the ground does not match the romanticised propaganda espoused online. A common theme is around a lack of healthcare, particular around childbirth.
Q: Are they free to leave?
A: Ms Kitteridge would not comment yesterday on whether any of the New Zealand woman who made the journey had returned, but said the SIS would "of course ... maintain an interest in those people" if they did.
The agency was concerned about the women and what they were doing in the war zone, she said.
"There would be really significant concerns about what they are being exposed to, the conditions that they are, their ability to get away if they want to or how heavily radicalised or exposed to acts of barbarism they might be seeing."
There are fears that some widowed women will return to their home countries radicalised and tasked with carrying out jihad for Isis.
Life under control of Isis fighters is difficult to leave, with widows pressured into remarrying, others isolated from the families they left behind. Two Austrian teens, Samra Kesinovic, 16, and Sabina Selimovic, 15, who ran away to Syria are reportedly now dead.
However, some women have escaped the Isis' clutches, and then rescued by aid groups.