In the Bible we see plenty of examples of when Israel rebelled against God and they filled their lives with sin and wickedness then as a nation they became weak and vulnerable to their enemies so that their enemies could do as they wanted with Israel because the nation had become weak.
And we can see that also happened on 9-11. That happens in many ways in the history of our nation. When we're weak because of our rebellion against God then our enemies are stronger in comparison.