Three British schoolgirls thought to be trying to join the Islamic State group are believed to have crossed from Turkey into Syria, British police said Tuesday.
The teens -- Kadiza Sultana, 16, and Amira Abase and Shamima Begum, both 15 -- disappeared from their homes a week ago, flying from London to Istanbul.
Their families issued desperate public pleas for them to return. "We miss you. We cannot stop crying,'' said Abase Hussen, Amira's father, on British TV, holding a teddy bear his daughter gave to her mother for Mother's Day. "Please think twice. Don't go to Syria.''
In a statement Tuesday, London police said law enforcement officials searching for the girls "now have reason to believe that they are no longer in Turkey and have crossed into Syria." The statement said officers were continuing to work closely with Turkish authorities on the investigation.
On Monday, Turkish officials criticized Britain for taking too long to notify them about the girls. Deputy Prime Minister Bulent Arinc said he hoped the girls would be found, but that Britain, not Turkey, would be to blame if they were not.
The three teens are friends with a fourth girl from their school who police believe is already in Syria after she left Britain in December.
Lure of jihad
Thousands of foreigners from more than 80 countries have joined the ranks of the Islamic State and other radical groups in Syria and Iraq, many crossing through Turkey. Security officials estimate 500 or more people from Britain alone have traveled to Syria to join the conflict.
Most have been men, but women are also being radicalized.
"The recent increase in the number of females going over to join ISIS specifically is something that was really quite unexpected, and at the moment, quite poorly understood," Sam Mullins, counterterrorism professor at the George C. Marshall European Center for Security Studies, told VOA.
As the Islamic State group continues to build up its society in Syria and Iraq, the draw for women coming from abroad is as varied as it is for men, said Mullins, who studies the flow of foreign fighters from Europe, North America and Australia to terror groups.
"For the most part, [the women] do understand the roles they are likely to play," he added - and that role, anecdotally, is not on the battlefield, but as homemaker, caretaker and wife. "The important thing to bear in mind is, they [Islamic State] really want to be able to create and maintain a state - they want as many people there as possible."
Traveling in groups - or at least planning to travel with others - is another commonality among the majority of foreigners joining the Islamic State group. Rarely will someone make the decision alone, said Mullins.
Another common thread defining the flow of foreign fighters: online propaganda and social media, which lure both male and female recruits.
In the wake of this latest instance, British Prime Minister David Cameron called on Internet companies to do more to address online extremism, saying the three girls appeared to have been radicalized while at home "in their bedrooms."