You're all off base. The way to paralyze America is not through a major attack -- 9/11 only served to mobilize the country.
America would be most vulnerable if attacked in the way that Israel is -- through a series of small attacks at shopping centers, restaurants, hotels, buses, schools, etc.
Israel has held up against this for the simple reason that these attacks are not only as old as the country, but actually pre-date it. It is a way of life for Israelis and while we are saddened with each one we accept them as part of life.
Americans are not prepared for this. If they become afraid to go about their daily routines, the country will collapse.