david begnaud, thank you. and turning now to afghanistan and more chaotic scenes at the kabul airport. evacuations are proceeding slowly, with thousands of americans still wanting and waiting to get out. and there are reports that taliban fighters are preventing afghan civilians from getting anywhere near that airport gate. cbs' david martin is monitoring the situation from the pentagon. >> reporter: u.s. combat troops lined up shoulder to shoulder behind concertina wire at the airport to keep back desperate afghans clamoring for a way out. ( gunfire ) a few times, warning shots had to be fired to keep the mob back. for now, the runways are clear, and transport planes have flown out a total of 5,000 people, mostly american citizens and afghans who once worked for the u.s. it could be the largest evacuation since the fall of saigon 46 years ago, and defense secretary austin acknowledged it's not moving fast enough. >> it's obvious we're not close