and they have a history of fighting one another. but every day, we have troops on the ground. these troops and innocent civilians at the airport face the risk of attack from isis-k from a distance even though we're moving back the perimeter significantly. >> we are sustaining the highest level of vigilance for an attack against the airport by isis-k or another terrorist group. >> they're real and significant challenges that we also have to take into consideration. the longer we stay, starting with the acute and growing risk of an attack by a terrorist group known as isis-k, an isis affiliate in afghanistan, which is a sworn enemy of the taliban, as well. every day we're on the ground is another day we know that isis-k is seeking to target the airport and attack both u.s. and allied forces and innocent civilians. >> it's hard to overstate the complexity and the danger of this effort. we're operating in a hostile environment in a city and