People everywhere look to the United States to use its remarkable power to help lift humanity up and to work for the common good.

On this International Day for the Abolition of Slavery let us reaffirm the inherent dignity of all men, women and children. And let us redouble our efforts to build societies in which slavery truly is a term for the history books.

Nuclear disarmament is the only sane path to a safer world.

With her courage and determination, Malala has shown what terrorists fear most: a girl with a book.

I am willing to take any measures when it comes to the fundamental principle of human rights.

I have been urging the leaders to listen to the aspirations and challenges of their own people, and engage in dialogue and take very bold measures. Normally, to their regret, these measures and bold reforms come too late, too little.

You are already leaders. Your ideas, your actions and your decisions make a difference. More than any other generation, you have a voice. Social networking is changing how we interact - and it can change our world. You are in touch with peers from around the world. You understand the power of instant communication. I appeal to you to use that power for the common good, the power of communication and the power of networking.