ISIS is using increasing numbers of women to evade security measures and spearhead a wave of attacks across Europe and the Islamic world as it loses territory in the Middle East.
Previously, female members of ISIS (ISIL, IS, Daesh) have been confined to support roles and kept away from the battlefield.
However, this policy appears to have been reversed in the summer, as military pressure on its main strongholds in Iraq, Syria and Libya intensified and substantial territory began to be lost.
Researchers describe a “drastic U-turn”.
Officials have repeatedly warned that ISIS would launch attacks as it retreated from earlier gains, the guardian Reports.
Since August, a series of plots involving women have been uncovered by security authorities in Europe and north Africa.
The new tactic poses a challenge for security organisations which already have difficulty penetrating extremist networks and identifying potential attackers.
“It’s a concern … There is constant evolution as the pressures on (ISIS) increase, so we are not complacent,” said one western European security official.
A plot in Paris in September, involving four women aged between 19 and 39, received significant media coverage.
The cell, organised by a known ISIS terrorists in France, was the first to be entirely female.
Two of the women had been listed as potential security risks by French intelligence agencies after attempting to reach Syria to join ISIS.
A third was recently married to a militant shot dead by police on the outskirts of Paris in June, after he stabbed two police officials to death at their home.
“If at first it appeared that women were confined to family and domestic chores by the terrorist organisation, it must be noted that this view is now completely outdated,” François Molins, a French prosecutor, told reporters after the four were arrested.
But a series of other plots around the world, which involve women playing “combat” roles, received less attention.
In August, Isis was reported to have deployed at least one female suicide bomber in Libya, while last month 10 alleged female attackers were arrested in Morocco.
All were in their teens, had sworn allegiance to ISIS, and were in possession of bomb-making material, officials said.