"Hayat Tahrir al Sham, a terror group linked to al-Qaida, overran Syria’s second largest city this week. Counterterrorism experts indicate it’s the strongest signal in the last few years that the terror group and its allies are rapidly gaining strength. In this week’s episode of “The Hunt with WTOP National Security Correspondent J.J. Green,” Hans Jakob Schindler, senior director of the Counter Extremism Project, said the group could soon become a problem for the U.S.”