No, the Pentagon was hit by a giant flying marshmallow.
You know it's true because of all the marshmallow bits they found all over the Pentagon lawn.
One other thing - Cruise missiles can be visible from the ground (for example, journos in Baghdad in 1991 reported seeing them flying down the streets) and look like missiles, not planes. Eyewitnesses who reported seeing the plane that hit the Pentagon would have been extremely unlikely to have confused a missile with a plane - they are very different looking things.
I bought a wagon-wheel the other day - the first one I've bought for over 25 years - and I noticed it was considerably smaller than they used to be!
I reckon that Burton's Biscuit company is a front for a CIA operation and has been secretly syphoning off a percentage of the wagon-wheel marshmallow for years in preparation for building the MMM (Mega Marsh Mallow).
There's no other rational explanation.