When federal agents apprehended eight men from Tajikistan — a Central Asian nation that borders Afghanistan — they were concerned the men could have been plotting a possible terrorist attack on U.S. soil, multiple sources familiar with the investigation told CBS News. 

The eight men residing in Los Angeles, New York, and Philadelphia were taken into custody earlier this month and charged with violating civil U.S. immigration law by Immigration and Customs Enforcement. They remain in ICE custody and face removal proceedings, according to two of the sources who spoke on the condition of anonymity because they were not authorized to speak publicly about the probe.