They could ask me.

Senate hearing, 9/11/07:

Senator Warner: Are you able to say at this time if we continue what you have laid before the congress here, this strategy, do you feel that that is making America safer?

General Petraeus: Sir I don't know actually.

David Brooks today:

I asked [Defense Secretary Robert Gates] whether invading Iraq was a good idea, knowing what we know now. He looked at me for a bit and said, "I don't know."

Hat tip to Steve M.