Have you seen the documentary on the life of Robert McNamara, Fog of War: Eleven Lessons from the Life of Robert S. McNamara?
One of the 11 lessons that McNamara gives is "Never answer the question that has been asked of you. Answer the question you wish you had been asked."
I heard that rule in action today on MPR's Midmorning program. Speaking about the genocide in The Sudan, Steven Forester, spokesman for the U.S. Committee for Refugees, suggested a number of things the US could do to stop the genocide, short of deploying military forces (which we seem to have a short supply of currently). One of his suggestions was a "No Fly Zone" over Darfur to stop the coordination between the militia and the Sudanese military pilots.
It took a few minutes, but the host finally asked Forester how the no fly zone would be enforced. He took a page from McNamara and talked about something, anything else instead.
You can listen here (RAM).