Secrets and the Americans....I know it should make you laugh..until you remember they managed to keep the lid on the A-12 program ( as in the predecessor to the YF-12/SR-71)until after they had retired the whole fleet (OK it ws only operational for a short while but still) to say nothing of the F-117 program..concpet, flight test FSD and production before anyone knew what it looked like for real....
If they want to they can like all of us keep a secret.....
No comment on 9/11 but lots on 911s...