In the meantime, - - -
While there has been no missile defense system, no rockets have been launched against the United States. Zero. None.
Squat. Do you know how many "squat" is? It's a big, fat, empty.
Oh, one thing. There was considerable damage done to areas of the US by an enemy usurping our own airplanes, but that was only after the appropriate government agencies had more than enough information to stop that, if only they had thought about it as much as novelists, and so on.
Think about it. For once.
Arf