Lots of people died.
The best policy has some bad repercussions.
The worst policy has some good consequences.
"Don't invade Poland," was not a coherent American strategy for ensuring a peaceful Europe. It was only such for Germany. Likewise "Don't fly hijacked planes into buildings," isn't a policy that the United States needs to implement.
American strategy informs American actions and can only indirectly influence non-American actions.
Noah Millman wrote:
Link (which includes additional good retrospectives) thanks to Ampersand.
This article may have more political content than is suitable for LW-- if you'd rather discuss it elsewhere, I've linked it at my blog. I've posted about it here because it's an excellent example of updating and of recognizing motivated cognition even if well after the fact.