Germany has organized the return of three women and 12 children from camps in northeastern Syria for humanitarian reasons.
Foreign Minister Heiko Maas on Sunday did not further identify the women or children, who were flown back to Germany on Saturday.
However, the German weekly Bild am Sonntag reported that all three women had left Germany in recent years to join the extremist ISIS group Syria. The paper identified the women as Merve A., Yasmin A. and Leonora M.
Also Sunday, Germany's federal prosecutor's office said a German citizen by the name of Leonora M. had been arrested upon her arrival at Frankfurt airport. It said she is accused of membership in the foreign terrorist group ISIS and allegedly committed crimes against humanity.
Maas said he was "very relieved" about the return of the 12 children and three of their mothers.
"These are humanitarian cases, especially orphans and children with illnesses - cases in which the departure was urgently needed," Maas said.
"This good news just before Christmas makes us confident that we will be able to organize the return of further cases as well," he said adding that the government would advocate the return of others in coming weeks and months.
Maas said the return was organized in cooperation with Finland, which brought home six children and two women.
Hundreds of Europeans - many of them young women - left the continent in the last couple of years to join ISIS and fight in Syria and Iraq. Several died, others were arrested and detained by Turkish, Kurdish, or Iraqi authorities who have been eager to deport them and their children back to Europe.
European governments, however, have been reluctant to take back the often radicalized Islamic State supporters and sentiment is running high across Europe against the returnees.