mission. we're now under 285. >> reporter: obama brusquely dismissed romney as a clueless neophyte in national security. >> well, governor, we also have fewer horses and bayonets because the nature of our military has changed. >> reporter: country after country, crisis after crisis they slugged it out. the president offered a dramatic contrast. >> when i came into office, the world was divided. iran was resurgent. iran is at its weakest point economically, strategically, militarily than since -- than in many years. when it comes to going after osama bin laden, you said well any president would make that call. but when you were a candidate in 2008 as i was, i said if i got bin laden in our sights, i would take that shot. you said we shouldn't move heaven and earth to get one man. >> reporter: mitt romney tried to undermine the president's osama bin laden triumph with a blunt line. >> i congratulate him on taking out osama bin laden and going after the leadership in al qaeda, but we can't kill our way