until these sailors become navy s.e.a.l.s. >> that sequence of developing confidence is part of s.e.a.l. training. >> reporter: ryan zincke was a s.e.a.l. team commander. >> that's why at the end, they're tough guys. when they go toe to toe against somebody there is an absolute belief that they will win. failure isn't an option and guys will not give up, ever. ever. >> reporter: that's why when the target is osama bin laden the president turns to the navy s.e.a.l.s and a special unit, s.e.a.l. team six. wasden and zincke were both members. >> s.e.a.l. team six is a different unit from the rest of the s.e.a.l. teams and as much as they concentrate primarily on one thing -- counter-terrorism, hostage rescue. >> it's the nation's 911. it's our nation's best that is