Soledad,

The 1994 assault weapons ban does not address fully automatic weapons at all. It addresses semi automatic weapons and bans/regulates them based on appearance, not function.

Fully automatic weapons, with or without the assault weapons ban, are legal to own and use, but highly restricted and taxed. Terrorists are not going to buy weapons at the local gun store, the regulations are too tight. It's easier to smuggle them into the country when they enter. Besides, an automatic weapon does less damage than many objects that one could legally obtain with no restrictions, like an 18 wheeler, a bag of fertilizer, etc. Legislation does not stop people from doing these things.