riskier all the time. talan from leaving the country, and one taliban spokesman told cbs' roxana saberi that any attempt to extend the rescue mission would be considered a violation. >> so in light of that violation, it is up to our leadership to decide what to do. >> reporter: c.i.a. director william burns has been negotiating in kabul with the taliban's de facto leader, as the u.s. military picks up the pace, evacuating 20,000 people a day from kabul's airport, the flights taking off every 45 minutes. that brings the total number of evacuees since mid-month to more than 70,000. >> we are currently on a pace to finish by august the 31st. i've asked the pentagon and state departor plans to adjust the timetable, should that become necessary.