New Delhi, Feb. 14 -- Inside a heavily guarded detention facility in Baghdad, men from scores of different countries and nationalities were brought one after another into interrogation rooms and questioned by Iraqi officers.

The prisoners are suspected members of the militant Islamic State group recently transferred from Syria to Iraq at the request of Baghdad - a move welcomed by the U.S.-led coalition that had for years fought against IS.

Over a period of several weeks, the U.S. military escorted more than 5,000 IS detainees from 60 different nationalities from prisons in northeastern Syria run by the U.S.-backed and Kurdish-led Syrian Democratic Forces, to Baghdad.

The transfers have helped calm fears that the fighting in Syria woul...