Abu Ubayd al Qurashi(Strategist/Analyst loyal to Al Qaeda and similar Jihadi organizations)says:

“Strategically, in the raid of 9/11, Al Qaeda destroyed the pillars of the American Defense Strategy which neither the Soviet Union nor any other enemy nation managed to do before.

These pillars are:

Early warning, Preventive attack and the Principle of Deterrence.

This raid also caused America’s abilities to be distributed on a greater surface area as it forced it to distribute its forces in many sites without making any achievements in any of them.”