After the Berlin Wall came down I visited that city and I will never forget it. The abandoned checkpoints. The sense of excitement about the future. The knowledge that a great continent was coming together. Healing those wounds of our history is the central story of the European Union.

You don't have to be a brilliant historian to know that in Europe, messing with countries' borders, messing with their self-determination, their ability to choose their own futures, this is extremely dangerous, and that's why I think it is important to stand up to Putin.

I think the country requires fresh leadership. I do not think I can be the captain to take the country to its next destination.

Yes, America must do the right thing, but to provide moral leadership, America must do it in the right way, too.

In situations of military conflict, civil strife, lawlessness, bad governance, and human rights violations, terrorists find it easier to hide, train and prepare their attacks.

During a time of war, we ask our troops to give their best even to the point of sacrificing their own lives. When compared against that, how much of a sacrifice is it for a president to engage in a possibly contentious debate with Congress about whether military action is a good idea?

I am making this statement as an act of wilful defiance of military authority, because I believe that the War is being deliberately prolonged by those who have the power to end it.

Winning the Revolutionary War, or the Civil War, or World War II were the turning points in our history, the sine qua non of our forward progress.