With the defeat of the Islamic State and the militants’ loss of territory in the Middle East, countries across Europe have had to grapple with the return of those associated with the group. Turkey’s decision to release ISIS detainees has also forced Western European nations to confront a problem they had long sought to avoid: what to do about the potential return of radicalized, often battle-hardened Europeans to countries that do not want them back.

By November 2019, there were 12,300 foreigners detained in camps in Syria, including over 8,700 children from more than 40 nations, according to estimates by the charity Save the Children. A report from the Washington Institute for Near East Policy showed similar figures.

Preparation to repatriate the woman to Norway began in October, according to officials. Since March 2019, she had been held in the Al-Hol camp in northeastern Syria, along with thousands of other women and children. (Four other ISIS-affiliated women from Norway remain in Syrian camps.)

Officials said that she was married to an ISIS fighter named Bastian Vasquez, a Norwegian with a Chilean background. He went missing under unclear circumstances in 2015. Later, the woman married another ISIS fighter. Both of their stories were told by the author Asne Seierstad in her biography of foreign fighters in Syria, “Two Sisters.” In the book, the woman is identified by the name “Emira.”

Norway’s Ministry of Foreign Affairs said that she and her children had been repatriated because of fears that her son was seriously ill.

Prime Minister Erna Solberg of Norway told the state broadcaster NRK on Thursday, “What is important is that the presumably ill child now can get medical treatment in Norway.”