first of all, isis-k, the group that carried out the attack last week, is actually an enemy of the taliban and they have clashed with them before. so in some ways this is kind of for domestic/political consumption to convey the idea they're in charge and they're not tolerating these kinds of things. also, the u.s. reserves the right to go after terrorist groups that have attacked americans. so i think we could see more strikes like this in the future if the opportunities present themselves and if u.s. officials believe that they're worth taking against this group that carried out that horrendous bombing last week. in the meantime, the u.s. military is beginning to withdraw. what the pentagon calls retrograde operations, and the pentagon press secretary, john kirby, was asked about this today at the briefing. let's hear what he had to say. >> reporter: have u.s. troops begun retrograde withdrawal from