Any military commander who is honest with himself, or with those he is speaking to, will admit that he has made mistakes in the application of military power. He's killed people unnecessarily—his own troops or other troops, through mistakes, through errors of judgment. A hundred, or a thousand, or ten thousand, maybe even a hundred thousand. But he hasn't destroyed nations.

And the conventional wisdom is: don't make the same mistake twice. Learn from your mistakes. And we all do. Maybe we make the mistake three times, but hopefully not four or five.

They'll be no learning period with nuclear weapons. Make one mistake and you're going to destroy nations.