Image copyright Facebook Image caption Khadijah Dare, here with her husband Abu Bakr, tweeted that she wanted to kill a Western hostage

Recent news stories, such as those of the missing school girl Yusra Hussien, university student Aqsa Mahmood and twins Salma and Zahra Halane, have triggered concerns about the radicalisation of Muslim women in the UK.

It's estimated that some 50-60 women from the UK have travelled to Syria via Turkey to join the militant extremist movement Islamic State (IS). On arrival they join others from a range of countries, including the US, Austria, France, the Netherlands, Canada, Norway and Sweden. Just why are women from these Western countries joining up?

In the case of Yusra Hussien, it is unclear whether she has been radicalised or indeed whether she has even travelled to Syria (although police believe this to be likely).

For many of the others, their stories are available on social media - on Twitter, tumblr, LinkedIn, and ask.fm.

From these stories, it is clear that the influence of social media networks is considerable. They offer the women advice, support, help with travel, and are a source of propaganda for IS, presenting idealised notions of an Islamic life and jihad.

Image copyright PA Image caption University student Aqsa Mahmoud travelled to Syria and married an IS fighter

Image copyright AP Image caption Police fear Yusra Hussien, who went missing last month, has travelled to Syria after becoming radicalised

Initially a significant number of women travelling to Syria went to join their husbands, who were already fighting for IS.

For example, Khadijah Dare - the 22-year-old woman from south London who notoriously tweeted that she wanted to be the first female jihadi to kill a Western hostage - went to live in Syria after arranging to marry a Swedish IS fighter, Abu Bakr.

'Jihadi brides'

In these cases, family is an important facilitator for their journey.

In other cases, such as those reported recently, online networks facilitate their travel and help co-ordinate them with expat communities once they arrive. International travel is accessible and affordable, and made easier by this online planning.

Stethoscope around my neck and kalash on my shoulder. Martyrdom is my highest dream Umm al-Baraa, Malaysian medic

The notion of "jihadi brides" travelling to Syria to marry IS fighters has gained currency in recent reports in the western media.

Families in France whose daughters have gone to Syria have received phone calls from Syrian men asking for their daughters' hands in marriage, and the online accounts of male fighters seem bombarded by requests from women wanting to be their wives.

Mia Bloom from the Center for Terrorism and Security Studies at the University of Massachusetts Lowell provocatively argued that women are seen as little more than "baby factories" in the desire to populate the new "purist" Islamic state.

However this does not mean the young women simply want to find a husband. The "jihadi bride" concept is only part of the story.

There is another side to their decision to travel. Women are joining IS because it provides a new utopian politics - participating in jihad and being part of the creation of a new Islamic state.

Violence and domesticity

The leader of IS has attempted to recast the movement away from just one of fighters, and called for doctors, engineers, and builders to join them in creating a pure Islamic state.

Image copyright AFP

There is great deal of romanticism in women's accounts about being part of this political project with a new version of a political Islamic "good life" built upon a particular idea of Islam and Sharia law.

In this new 'state', women have all kinds of jobs and functions. For example, in the Syrian city of Raqqa they can join the so-called Al-Khansaa brigade, the all-female moral "police force" allegedly set up by a British woman.

There are images of women carrying AK47's, wearing a suicide belt and holding a severed head. But they are also cooking, making Nutella pancakes, doing housework, meeting each other for coffee, and being mothers and carers.

It is this combination of violence and domesticity that many find jarring. A female Malaysian medic, now known as Umm al-Baraa, tweeted in January: "Stethoscope around my neck and kalash on my shoulder. Martyrdom is my highest dream".

These, then, are the political drivers which pull some Muslim women towards IS. But there are push factors too.

Naive romanticism

The perceived failure of Western states to give young Muslims a sense of belonging, purpose and value as Muslims and citizens is striking in the online accounts of these women jihadis.

In an instance of this, one Dutch woman in Syria called Khadija (speaking to the US-based website Al-Monitor) said: "I always wanted to live under Sharia. In Europe, this will never happen."

The women talk about the failings of Western societies, speak negatively about restrictions on how they can practise Islam (for example, the ban on wearing the burqa in France), and criticise the political system.

Yet paradoxically, while quotes from the Koran are woven into their accounts, there is very little sign of deep knowledge about the conflict itself, or indeed about Sharia law or Islam.

The stories of the women who have travelled from Western countries to Syria to join IS highlight the combination of political and personal reasons behind their decision. But they also indicate that their motivation is characterised by a naive romanticism.

Dr Katherine Brown is a lecturer in the Defence Studies Department at King's College London. In her work, she has examined the roles and portrayal of women in terrorism, counter-terrorism, and violent politics, and investigated Muslim women's radicalised political activism