>> brangham: rebekah wolff is one of the young female recruits who wants to join the fight to go into one of the jobs that for generations had been blocked to women... until now.¡ low altitude air defense' is what she wants to do: basically shooting shoulder-fired" stinger" missiles at enemy aircraft. that's what you want to be doing, shooting stinger missiles? >> yeah! >> brangham: why that? >> because it'd be cool. (laughs) and not a lot of females have had that opportunity until now, really, so that's exciting. >> ten, nine, eight... >> brangham: of course, that's a long way off. for now, she's not only got to prove herself at boot camp, but she'll have to pass tougher physical standards than females have ever had to meet before. on the first night, after filling out some paperwork, recruits are required to make one phone call home. >> this is recruit rivera! >> brangham: they're instructed to shout five scripted lines into the phone, nothing more. >> thank you for your support! goodbye for now! >> louder! louder! >> brangham: drill instructors intentionally create this sense of ch

>> reporter: 18-year-old rebekah wolff is three weeks into marine corps boot camp at parris island, southolina. she's one of the few young women who want to enter the combat positions that for years have been shut to women. she wants to be an air-defense gunner, to shoot stinger missiles. but first, it's the basics of knife fighting. ( whistle ) >> marine corps! >> we see how slashing right down the center of their chest, right? >> yes, sir! >> right down the center of their chest, understand that. >> reporter: these early weeks of boot camp are tough. recruits are still getting used to the rigors of marine training. they don't sleep much, and many haven't been away from home for this long. recruit wolff admits she's having a hard time. i know it's still early in your training. how do you feel like you're doing? >> i feel like i could do better. i was a lot better at home. but probably because i get a lot more sleep and i eat a lot more than what i do here. >> reporter: what have you been telling mom and dad? >> in all honesty, i tell my mom and dad that i want to come home. and that i ca