Immediately after the terrorist attacks on the Pentagon and World Trade Center, NATO members unanimously voted their support for the United States under Article V of the Washington Treaty. This unprecedented action, the first time such a vote has occurred in NATO's history, underscores the vitality of the Atlantic Alliance and its tremendous strategic value for its members. This vote conferred great legitimacy upon any response that the United States will make to those attacks and reminded us that the solidity of NATO allows the United States to defend its interests on the world stage with great confidence about European security. Nevertheless, the Alliance is not a wholly untroubled or static relationship. In the first half of 2001, there were numerous public signs of stress among the allies as they faced new challenges. Many of the issues involved in these tensions are particularly important to the future of European security and must be resolved for NATO to move forward...