British women who have travelled to Iraq and Syria to create an "Islamic utopia" could return home to carry out attacks as the conflict drags on, experts have warned.
An investigation into why Western women are joining Islamic State (IS) revealed some were now willing to go against the terror group's strict rules banning them from acts of violence.
Umm Ubaydah, a female European jihadist, questioned on social media whether she could "pull a Mulan and enter the battlefield", while another British woman, Umm Khattab, described how she put on an explosive belt after hearing gun shots, according to the report.
The study, by the London-based Institute for Strategic Dialogue, also found many Western women in IS were "desensitised" to the brutal beheadings carried out by the militants, including one who described the murder of American aid worker Peter Kassig and 18 Syrian hostages as "gut-wrenchingly awesome".
The report's authors said: "It is possible to suggest that, as the conflict drags on, the death of male fighters and the deaths of the migrant children could be a potential trigger which propels the women into changing roles.
"They may wish to strike at the 'near enemy' or even return home to strike at the West. The women's social media postings indicate that a sudden shift in roles is possible."
The number of Western migrants who have travelled to Iraq and Syria to join IS is believed to be around 3,000, including as many as 550 women, according to the study.
The report, which identified six British women who have travelled to the region, gathered evidence from social media accounts including Twitter and Tumblr, photographs, online interactions and media reports.
Ubaydah's mention of "Mulan" - the ancient Chinese figure who impersonates a man to replace her father in the army - is a "clear reference to a Disney film" and a reminder that the women have "grown up around Western films and music", the report said.
According to the study, the women "celebrate the violence of Isis unequivocally".
One British woman, Umm Hussain - named in reports as mother-of-two Sally Jones from Kent - tweeted: "Know that we have armies in Iraq and an army in Sham of angry lions whose drink is blood and play is carnage."
Another woman, who tweeted about the murder of Mr Kassig, said: "So I finally watched #IS latest video, OMG! ... Gut-wrenchingly awesome."
One woman tweeted: "So many beheadings at the same time, Allahu Akbar (God is the greatest), this video is beautiful."
Another woman, who watched a different beheading video, wrote: "'I was happy to see the beheading of that kaafir (non-believer), I just rewinded to the cutting part," before calling for "more beheadings please!", according to the study.
The report said: "There is no doubt, therefore, that the women who migrate to the territory controlled by Isis revel in the gore and brutality of the organisation.
"They appear desensitised to the horrific nature of the violent acts being committed."
Many "talk at length about the oppression of Muslims throughout the world" and often post gruesome and distressing images of violence against Muslims on their Twitter profiles and blogs, the report found.
They hope the region will develop into their vision of an "Islamic utopia" and believe that it is their mandatory religious duty, the study found.
There is also evidence to suggest that women's families have a "strong influence" in persuading them not to join IS, the report said.
Umm Layth - the name used by 20-year-old Aqsa Mahmood from Glasgow - tweeted: "When you hear them sob and beg like crazy on the phone for you to come back it's so hard."
In September, her parents Muzaffar and Khalida Mahmood said they were horrified that their "sweet, peaceful, intelligent" child had joined jihadists in Syria and urged her to come home.
The next month, parents of teenage girls Samya Dirie and Yusra Hussien also made emotional appeals for their safe return following fears they had travelled to Syria.
Yusra, 15, left her home in Easton, Bristol, and is thought to have met up with a 17-year-old Samya from London and boarded a plane to Turkey before the pair tried to cross the border with the war-torn state.
It is unclear how the teenagers, who are both from Somali families, met but they both vanished from their homes amid concerns they had been radicalised.
The report concludes that the threat posed by women in IS "is a different one than that posed by their male counterparts".
"They support male fighters in a non-military capacity and encourage attacks on the West by those who cannot travel," the authors said. "They demonstrate support for brutal violence equal in its strength to the men of Isis.
"They also demonstrate a capacity and willingness to engage in violence and even suicide attacks should circumstances change."