Five years ago, then as a candidate for U.S. president, Mr. Barack Obama made a triumphant appearance in Berlin. That speech drew 200,000 people and traced a direct line between the Obama candidacy and the power and imagery of U.S. President John F. Kennedy, who made a similar address 50 years earlier.
In an attempt to re-energize his agenda, Mr. Obama last week returned to Berlin and reasserted his vision of a world without nuclear weapons. That dream continues to animate the president — and remains controversial, as divisive as it is ambitious.
Just after taking office, Mr. Obama delivered a speech in Prague that outlined his vision of a world without nuclear weapons. In that address, he conceded that his goal would not be realized for many years, most likely not even within his lifetime, but he insisted — rightly — that such "distant" objectives must not be abandoned. The end of the Cold War may have ended the threat of nuclear annihilation, but the continuing existence of nuclear arsenals and the spread of their weapons pose a danger that is real and growing.