DENVER (TIP): The case of three teenage girls being investigated for trying to join Islamic State militants poses vexing questions for US officials about the use of social media by terror groups to recruit people inside the United States, experts said on October 23. A Colorado school official said the Denver area girls — two sisters ages 17 and 15, and a 16-year-old friend — were victims of an online predator who encouraged them to travel overseas and eventually to Syria.

Mia Bloom, a professor of security studies at the University of Massachusetts-Lowell, said the girls’ story so far suggests how Islamic extremists have mastered social media to prey on younger and younger women with “Disney-like versions of what it is like to live in the caliphate,” complete with promises of husbands and homes. At least one of the girls was communicating with someone online who encouraged the three to travel to Syria, said Tustin Amole, a spokeswoman for the Cherry Creek school district where the girls attend high school.

Fellow high school students told school officials that the girls had been discussing travel plans over Twitter, Amole said. The girls were detained at an airport in Frankfurt, Germany, and sent home over the weekend. They were interviewed by the FBI and returned to their parents in suburban Aurora. Those in the tight-knit east African community where they live said the sisters are of Somali descent and their friend is of Sudanese descent. “There’s no indication they had been radicalized in a way that they wanted to fight for ISIS,” Amole said.

A US official said evidence gathered so far made it clear that the girls were headed to Syria, though the official said investigators were still trying to determine what sort of contacts they had in that country. Another US official said that investigators were reviewing evidence, including the girls’ computers. The officials spoke on the condition of anonymity because they were not authorized to discuss the ongoing investigation by name.

“Social media has played a very significant role in the recruitment of young people,” said FBI spokesman Kyle Loven in Minneapolis, home to the largest Somali community in the US Authorities there have been concerned about terror recruiting of the young for years. “What we’ve experienced here in Minneapolis is that young, disaffected youth who exist primarily on the fringes of society — they seem to be more susceptible to this type of propaganda, unfortunately,” Loven said. Terror recruiting has been a problem for years in Minneapolis. Since 2007, roughly 22 young Somali- Americans have traveled to Somalia to take up arms with al-Shabab, an al- Qaida linked group. Those were all men.