several rockets are also locally produced in gaza. israeli air strikes now aiming at rocket launch sites, production factories and other militant targets. israel's main defense, this system called the iron dome. strategically placed units around israel launched missiles against incoming rockets that appear headed for population centers. so far, israel says it's worked well much of the time, but hamas is looking for vulnerability. >> i think what they're trying to do is fire as many as they can in a short period of time because that overwhelms the iron dome sensors. >> the u.s. has spent nearly $9 million on the iron dome, just part of the $3 billion in u.s. funding for israel's defenses. the pentagon is keeping a close eye on whether israel will launch a ground incursion into