"Many countries either don’t know or don’t disclose the number of citizens who traveled to join ISIS — including all countries in the top 10, save for Russia — and many don’t make public the number of returnees brought to trial. “Lack of transparency translates to lack of accountability,” said Fink of The Soufan Center. “It helps countries not to be transparent, because they don’t want to talk about what they’re doing when [fighters] come back.” Fighters who do come home, either by government intervention or on their own, are considered a “great security threat for countries upon their return,” said Gina Vale, co-author of a 2019 International Centre for the Study of Radicalisation (ICSR) report that offers the most recent estimates of individuals affiliated with ISIS by country."