Friday's suicide bomb attack in Afghanistan was the bloodiest assault since U.S. forces left the country. It came less than a week after a bomb blast killed at least five people outside a mosque in Kabul. There have also been other violent incidents since the Taliban came back to power. Last month, a spate of attacks hit the eastern city of Jalalabad. Local reports said at least six Taliban personnel and several civilians were killed in a span of two days. ISIS claimed responsibility. It was also responsible for a suicide bomb attack outside Kabul airport just days before the foreign troops' withdrawal. At least 170 people, including 13 U.S. military personnel, were killed in the blast and suspected U.S. army gunfire that followed. Hamza Momen Hakimi, a professor of law and political science at Salam University, share his insights on the motives behind these attacks.