The two superpowers that faced each other across the wall of this city came too close too often to destroying all we have built and all that we love. With that wall gone, we need not stand idly by and watch the further spread of the deadly atom.
Link to relevant relevant section of Obama's "A World that Stands as One" speech in Berlin onn 24 July 2008:
"This is the moment when we must renew the goal of a world without nuclear weapons. The two superpowers that faced each other across the wall of this city came too close too often to destroying all we have built and all that we love. With that wall gone, we need not stand idly by and watch the further spread of the deadly atom. It is time to secure all loose nuclear materials; to stop the spread of nuclear weapons; and to reduce the arsenals from another era. This is the moment to begin the work of seeking the peace of a world without nuclear weapons."